Nanotechnology: The New Features

Abstract

Nanotechnologies are attracting increasing investments from both governments and industries around the world, which offers great opportunities to explore the new emerging nanodevices, such as the Carbon Nanotube and Nanosensors. This technique exploits the specific properties which arise from structure at a scale characterized by the interplay of classical physics and quantum mechanics. It is difficult to predict these properties a priori according to traditional technologies. Nanotechnologies will be one of the next promising trends after MOS technologies. However, there has been much hype around nanotechnology, both by those who want to promote it and those who have fears about its potentials. This paper gives a deep survey regarding different aspects of the new nanotechnologies, such as materials, physics, and semiconductors respectively, followed by an introduction of several state-of-the-art nanodevices and then new nanotechnology features. Since little research has been carried out on the toxicity of manufactured nanoparticles and nanotubes, this paper also discusses several problems in the nanotechnology area and gives constructive suggestions and predictions.

Full text

Nanotechnology: The New Features
Gang Wang
Dept. of Computer Science and Engineering
University of Connecticut
Email: g.wang.china86@gmail.com or gang.wang@uconn.edu
Abstract—Nanotechnologies are attracting increasing invest-
ments from both governments and industries around the world,
which offers great opportunities to explore the new emerging
nanodevices, such as the Carbon Nanotube and Nanosensors. This
technique exploits the specific properties which arise from struc-
ture at a scale characterized by the interplay of classical physics
and quantum mechanics. It is difficult to predict these properties
a priori according to traditional technologies. Nanotechnologies
will be one of the next promising trends after MOS technologies.
However, there has been much hype around nanotechnology, both
by those who want to promote it and those who have fears about
its potentials. This paper gives a deep survey regarding different
aspects of the new nanotechnologies, such as materials, physics,
and semiconductors respectively, followed by an introduction of
several state-of-the-art nanodevices and then new nanotechnology
features. Since little research has been carried out on the toxicity
of manufactured nanoparticles and nanotubes, this paper also
discusses several problems in the nanotechnology area and gives
constructive suggestions and predictions.
I. INTRODUCTION
Nanotechnology, introduced almost half a century ago, is
an active research area with both novel science and useful
applications that has gradually established itself in the past
two decades. Nanotechnology – a term encompassing the
science, engineering, and applications of submicron materials
– involves the harnessing of the unique physical, chemical, and
biological properties of nanoscale substances in fundamentally
new and useful ways. The economic and societal promise of
nanotechnology has led to investments by governments and
companies around the world. The complexities and intricacies
of nanotechnology, still in the early stage of development, and
the broad scope of these potential applications, have become
increasingly important [1].
A nanometer is one-billionth of a meter. For example, a
sheet of paper is about 100,000 nanometers thick; a single gold
atom is about a third of a nanometer in diameter. Dimensions
between approximately 1 and 100 nanometers are known as
the nanoscale.
Nanotechnology is the understanding and control of matter
at the dimensions between approximately 1 and 100 nanome-
ters, where unique phenomena enable novel applications. En-
compassing nanoscale science, engineering and technology,
nanotechnology involves imaging, measuring, modeling, and
manipulating matter at this length scale. The transformative
and general purpose prospects associated with nanotechnology
have stimulated more than 60 countries to invest in national
nanotechnology research and development programs [2]. Un-
usual physical, chemical, and biological properties can emerge
in materials at the nanoscale. These properties may appear
dramatically different in important ways from the properties
of bulk materials and single atoms or molecules [3]. Using
structures designed at this extremely small scale, there exist
opportunities to build materials, devices, and systems with
nano-properties that can not only enhance existing technolo-
gies but also offer novel features with potentially far-reaching
technical, economic, and societal implications [4].
Nanotechnology products can be used for the design and
processes in various areas. It has been demonstrated that nan-
otechnology has many unique characteristics, and can signifi-
cantly fix the current problems which the non-nanotechnology
faced, and may change the requirement and organization of
design processes with its unique features [5].
Nanotechnology deals with the production and applications
at scales ranging from a few nanometers to submicron dimen-
sions, as well as the integration of the resulting nanostructures
into larger systems [6]. It also involves the investigation of
individual atoms. Particularly, the conventional analytic aspects
of nanotechnology must yield a certain synthetic approach,
which is similar with non-nanotechnology. This action will
be conducive to the creation of new functions exhibited by
nanoscale structural units through their mutual interactions,
even though these functionalities are not properties of the
isolated units. We can use the term nanoarchitectonics to ex-
press this innovation of nanotechnology [7]: it is a technology
system aimed at arranging nanoscale structural units, a group
of atoms, molecules, or nanoscale functional components,
into a configuration that creates a novel functionality through
mutual interactions among those units.
These very small structures in nanoscale are intensely
interesting for many reasons [8]:
1) Many properties mystify us. For example, how do
electrons move through organometallic nanowires?
2) They are challenging to make. For example, synthe-
sizing or fabricating ordered arrays and patterns of
nanoscale units poses fascinating problems.
3) Studying these structures leads to new phenomena,
since many nanoscale structures have been inaccessi-
ble and/or off the beaten scientific track.
4) Nanostructures are in a range of sizes in which quan-
tum phenomena, especially quantum entanglement
and other reflections of the wave character of matter,
would be expected to be important.
5) The nanometer-sized, functional structures that carry
out many of the most sophisticated tasks open up an
exciting frontier of biology.
Many nanotechnology advocates – including business exec-
utives, scientists, engineers, medical professionals, and venture
capitalists – assert that in the longer term, nanotechnology, es-
arXiv:1812.04939v1 [cs.ET] 8 Dec 2018

pecially in combination with information technology, biotech-
nology, and the cognitive sciences, may deliver revolutionary
advances [1].
One set of considerations revolves around how nanotech-
nology is characterized, and how nanotechnology is understood
as the emphasis moves toward the nano-era. In the discussion
of the nano-era, there are divergent approaches to define and
characterize the corresponding new features.
The rest of this paper is organized as follows: Section II
briefly describes the basics of nanotechnology. Section III
presents the new features of nanotechnology. Section IV de-
scribe several nanotechnology devices. Section V discusses
the problems and prediction of nanotechnology. Section VI
concludes this paper.
II. NANOTECHNOLOGY BASICS
Nanotechnology is the creation of materials and devices
by controlling matter at the levels of atoms, molecules, and
super-molecular structures [9], which means that it is the use
of very small particles of materials to create new large-scale
materials [10].
Nanotechnology whose form and importance are yet unde-
fined is “revolutionary nano”: that is, technologies emerging
from a new nanostructured material, or from the electronic
properties of quantum dots, or from fundamentally new types
of architectures – based on nanodevices – for use in compu-
tation and information storage and transmission. Nanosystems
that use or mimic biology are also intensely interesting.
Even more thorough definitions and concepts of nanotech-
nology have been used by researchers in different areas as
well, however, the key issue is the size of particles because the
properties of materials are dramatically affected by the scale of
the nanometer(nm), 10−9meter(m). Actually, nanotechnology
is not a new science or technology with current development
as we spoke of above. The research on nanotechnology has
been very active in the recent two decades for two reasons.
One is the interesting features at the nanoscale, as we dis-
cussed in section I, and the other is that the development and
application of nanotechnology rely on the rapid development
of other related sciences and technologies, such as physics and
chemistry.
According to [11], the subject of nanotechnology includes
“almost any materials or devices which are structured on
the nanometer scale in order to perform functions or obtain
characteristics which could not otherwise be achieved.”
To better understand the differences among various scales
with regards to nanotechnology, Table I shows the categories
of the scales and their corresponding related areas [12].
Just because materials can be made into very small particles
does not immediately mean that they have any practical use.
However, the fact that these materials can be made at this
nanoscale gives them the potential to have some interesting
properties. Table II gives the characteristic lengths in solid-
state science mode with respect to nanoscales [13].
According to quantum theory, materials at the nanoscale,
between 1 nm and 250 nm, lie between the quantum effects
of atoms, molecules and the bulk properties of materials. This
TABLE I. PARTICLE SCALE S VS. R ESEARCH ARE AS
Scales(meter) Research Areas(Not Inclusive)
10−12 Quantum Mechanics
10−9
Nanomechanics
Molecular Dynamics
Molecular Biology
Biophysics
10−6
Plasticity
Elastictiy
Dislocation
10−3Mechanics of Materials
10−0Structural Analysis
TABLE II. CH ARAC TE RIS TI C LEN GT HS IN S OL ID-S TATE SCI EN CE
MODEL
Field Property Scale Length
Electronics
Electronic Wavelength 10 ∼100 nm
Inelastic Mean Free Path 1 ∼100 nm
Tunneling 1 ∼10 nm
Optics
Quantum Well 1 ∼100 nm
Evanescent Wave Decay
Length
10 ∼100 nm
Metallic Skin Depth 10 ∼100 nm
Magnetics Domain Wall 10 ∼100 nm
Spin-flip Scattering Length 1 ∼100 nm
Superconductivity
Cooper Pair Coherence Length 0.1 ∼100 nm
Meisner Penetration Depth 1 ∼100 nm
Mechanics
Dislocation Interaction 1 ∼1000 nm
Grain Boundaries 1 ∼10 nm
Crack Tip Radii 1 ∼100 nm
Nucleation/Growth Defect 0.1 ∼10 nm
Surface Corrugation 1 ∼10 nm
Supramolecules
Kuhn Length 1 ∼100 nm
Tertiary Structure 10 ∼1000 nm
Secondary Structure 1 ∼10 nm
Catalysis Surface Topology 1 ∼10 nm
Immunology Molecular Recognition 1 ∼10 nm
nanoscale is called ‘No-Man’s-Land’ where many physical and
electrical properties of materials are controlled by phenomena
that have their own critical dimensions at the nanoscale.
Some ‘Nano’ definitions used in this paper are listed below.
1) Cluster: A collection of units (atoms or reactive
molecules) of up to about 50 units.
2) Colloids: A stable liquid phase containing particles in
the 1-1000 nm range. A colloid particle is one such
1-1000 nm particle.
3) Nanoparticle: A solid particle in the range of 1-
100 nm that could be noncrystalline, an aggregate
of crystallites or a single crystallite.
4) Nanocrystal: A solid particle that is a single crystal
in the nanometer range.
With nanotechnology, scientists and engineers can influ-
ence, by being able to fabricate and control the structure of
nanoparticles, the resulting properties and, ultimately, design
materials to give designed properties. The electronic properties
that can be controlled at this nanoscale are of great inter-
est [14]. The range of applications where the physical size of

the particle can provide enhanced properties that are of benefit
is extremely wide.
The science related to nanotechnology is new compared
with other sciences. However, nanosized devices and ob-
jects have existed on earth as long as life. The exceptional
mechanical performance of biomaterials, such as bones or
mollusk shells, is due to the presence of nanocrystals of
calcium compounds [15]. The history of technology suggests,
however, that where there is smoke, there will eventually be
fire; that is, where there is enough new science, important new
technologies will eventually emerge [8].
Nanotechnology has changed and will continue to change
our vision, expectations and abilities to control the materials
and design world. These developments will definitely affect
the semiconductor world and semiconductor materials. Recent
major achievements include the ability to observe structure
at its atomic level and measure the strength and hardness of
microscopic and nanoscopic phases of composite materials.
The new features of nanotechnology materials and elements
accordingly change nanotechnology usage, material force and
resistance, as well as their related fields and designs. Therefore,
it is essential and necessary to carefully study the new features
of current nanotechnology.
III. NEW FE ATUR ES
In this part, we will discuss the new features of nan-
otechnology from different scientific areas, such as materials,
physics and information technologies(ITs). Although some
new features in different areas may overlap in certain points,
these features will display different properties or characteristics
for specific areas.
A. Materials
Much of nanoscience and nanotechnology is concerned
with producing new or enhanced materials. Also, some
nanotechnology-enabled products are already on the market
and enjoying commercial success. These materials can behave
quite differently at the nanoscale to the way they do in bulk.
This is both because the small size of the particles dramatically
increase surface area and therefore reactivity, and also because
quantum effects start to become significant.
1) 3D Structure: Materials can be categorized by the
overall dimensionalities of the structure and the class of
compound. Many materials with nm dimensions in 1D have
been commercially successful [20].
Some recent novel developments include producing three-
dimensional(3D)(particles), two-dimensional(2D)(monolayer
films), one-dimensional(1D)(wires and tubes) and zero-
dimensional(0D)(dots) for functional applications. This
section will be concentrated on the developments and
structures of 3D carbon particles.
Carbon nanostructures have been the focus of much inter-
est and research since they were first observed in the mid-
1980s [16]. The football-shaped Buckminsterfullerene(C60)
and its analogs show great promise as lubricants and, thanks
to their cage structures, as drug delivery systems, as well as in
Fig. 1. Carbon C60 A Beautiful Molecule [19]
electronics. The same graphite sheet structure, which allows
electrical conductivity, was discovered in the early 1990s [17].
Fullerenes consist of 20 hexagonal and 12 pentagonal rings
as the basis of an icosahedral symmetry closed cage structure.
Each carbon atom is bonded to three others. The C60 molecule
has two bond lengths - the 6:6 ring bonds can be considered
as “double bonds” and are shorter than the 6:5 bonds. C60 is
not ”super aromatic” as it tends to avoid double bonds in the
pentagonal rings, resulting in poor electron delocalization. As
a result, C60 behaves as an electron deficient alkene, and reacts
readily with electron rich species. The geodesic and electronic
bonding factors in the structure account for the stability of
the molecule. In theory, an infinite number of fullerenes can
exist, their structure based on pentagonal and hexagonal rings,
constructed according to rules for making icosahedra [18].
Fig. 1 shows the 3D structure of the fullerenes [19].
2) Surface Ratio: In many sub-fields of nanotechnology,
advances in structured materials occur both by evolutionary
development of technologies and by revolutionary discoveries
that generated new approaches to materials synthesis. As the
particle size approaches to the 10 ∼100 nm range, the
surface to volume ratio increases and properties become size
dependent.
When the dimensions of materials are decreased from
macrosize to nanosize, significant changes in electronic con-
ductivity, optical absorption, chemical reactivity, and mechan-
ical properties occur. With the decrease in size, more atoms
are located on the surface of the particle. Also, these particles
can be considered as nanocrystals and the atoms within the
particle are perfectly ordered or crystalline.
Nanoparticles have a remarkable surface area, as shown in
Fig. 2. The calculated surface to nanoparticles bulk ratios for
solid metal particles vs. size is shown in Fig. 3. The surface
area imparts a serious change of surface energy and surface
morphology. All these factors alter the basic properties and
the chemical reactivity of the nanomaterials [6] [24] [25]. The
change in properties causes improved catalytic ability, tunable
wavelength-sensing ability and better-designed pigments and
paints with self-clean and self-healing features [26].
The Laplacian (a differential operator given by the di-
vergence of the gradient of a function on Euclidean space)
pressure, due to surface energy and the atomic structure of
the surfaces, impacts density, phase transition temperatures,

Fig. 2. Particle-size and specific-surface-area scale related to concrete
materials [27].
Fig. 3. Calculated surface to bulk ratios for solid metal particles vs size [28].
interface potential, and those properties that depend upon them.
However, when the particle size is below 10 nm, the quantum
effects dominate.
A number of research groups, notably UC Berkeley and
MIT, developed synthetic strategies to produce particles of
semiconductor and metal nanocrystals with particle diameters
in the range of 1 ∼50 nm. The new methods involve the
injection of molecular precursors into hot organic surfactants
and yield narrow size distributions, good size control and good
crystallinity of dispersable nanocrystals [21] [22] [23]. In this
size range, the optical absorption of compounds is a sensitive
function of particle size.
Exciting extensions of surfactant-mediated growth take
advantages of the fact that absorption of surfactants is depen-
dent on the atomic structure of the surface. The shapes of
nanodots are determined by differences in the surface energies
of the terminating atomic planes. By designing surfactants
that preferentially absorb on specific crystal planes and by
using more than one surfactant simultaneously, the direction
dependence of growth rate can be tailored. One can imagine
these as the basis of 3D functional structure as we mentioned
above.
3) Quantum Effects: Quantum mechanics is a fundamental
branch of physics which deals with physical phenomena at
nanoscopic scales, where the action is on the order of the
Planck constant. The name derives from the observation that
some physical quantities can change only in discrete amounts
(Latin quanta), and not in a continuous (cf. analog) way [29].
Several phenomena become pronounced as the size of
the system decreases. These include statistical mechanical
effects, as well as quantum mechanical effects, for example,
the “quantum size effect” where the electronic properties of
solids are altered with great reductions in particle size. This
effect does not come into play by going from macro to micro
dimensions. However, quantum effects can become significant
when the nanometer size range is reached, typically at dis-
tances of 100 nanometers or less, the so-called quantum realm.
Additionally, a number of physical (mechanical, electrical,
optical, etc.) properties change when compared to macroscopic
systems. One example is the increase in surface area to volume
ratio altering mechanical, thermal and catalytic properties of
materials. Diffusion and reactions at the nanoscale, nanostruc-
tures materials and nanodevices with fast ion transport are
generally referred to as nanoionics. Mechanical properties of
nanosystems are of interest in nanomechanics research. The
catalytic activity of nanomaterials also opens potential risks in
their interaction with biomaterials [30].
At the nanoscale, quantum confinement effects dominate
the electrical and optical properties of systems [31]. Much
interest is also focused on quantum dots, which are semi-
conductor nanoparticles that can be ’tuned’ to emit or absorb
particular colors of light for use in solar energy or fluorescent
biological labels.
Electrons localized in a quantum dot by a confinement
potential occupy atomic like states with discrete energy levels.
Therefore, a quantum dot with confined electrons is called
the artificial atom [32]. In the electrostatic or gated quantum
dots [33] [34], the confinement potential results from the
external voltages, applied to the electrodes, and band offsets.
The confinement potential is vary sensitive to the voltages
applied as well as the parameters of the nanostructure, in
particular, the geometry of the nanodevice and doping. The
electronic properties of the nanodevice are also determined
by the confinement potential. Therefore, the knowledge of the
realistic profile of this potential is important for a design of
the nanodevice with the required electronic properties and for
a theoretical description of the confined electron states [35].
Also, quantum dots are being developed as labels in
medical imaging and have potential in nano-opto electronics.
B. Physicals
Nanoparticles often have their own physical and chemical
properties that are very different from the same materials at
larger scales. The properties of nanoparticles depend on their
shape, size, surface characteristics and inner structure. They
can change in the presence of certain chemicals. The com-
position of nanoparticles and the chemical processes taking
place on their surface can be very complex. Nanoparticles can
remain free or group together, depending on the attractive or
repulsive interaction forces between them [36].

Fig. 4. Self-assembly processes of Nanoparticles [42].
1) Self-Assembly: Self-assembly is a phenomenon where
the components of a system assemble themselves sponta-
neously via an interaction to form a larger functional unit. This
kind of spontaneous organization can be due to direct specific
interaction and/or indirectly through their environment. Due to
increasing technological advancements, the study of materials
on the nanometer scale is becoming more important. The abil-
ity to assemble nanoparticles into a well-defined configuration
in space is crucial to the development of electronic devices
that are small but can contain plenty of information. The
spatial arrangements of these self-assembled nanoparticles can
be potentially used to build increasingly complex structures
leading to a wide variety of materials that can be used for
different purposes [39] [40] [41]. Fig. 4 shows the self-
assembly processes of nanoparticles.
With the continuous development of nanotechnology, the
possibility for the bottom-up production of nanoscale materials
may result in some kind of self-assembly of structures similar
to the self-assembly of phospholipid bilayers that resembles
cellular membranes. On the basis of current knowledge, how-
ever, the spontaneous formation of artificial living systems
through self-assembly and related processes, suggested by
some prominent commentators, is considered highly improba-
ble. The combination of self-replication with self-perpetuation
in an engineered nanosystem is extremely difficult to realize
on the basis of current scientific knowledge.
By the controlled self-assembly and self-organization of
molecular compounds and supramolecular entities, respec-
tively, it should be possible to design rationally and to construct
precisely nanoscale molecular devices with switching proper-
ties [37].
Nanotechnology is dependent on nanostructures that re-
quire creation and characterization. Two fundamentally differ-
ent approaches for the controlled generation of nanostructures
have evolved. On one hand, there is growth and self-assembly,
from the bottom up, involving single atoms and molecules.
On the other hand, there is the top-down approach in which
the powerful techniques of lithography and etching start with
large uniform pieces of material and generate the required
nanostructures from them. Both methods have inherent ad-
vantages. Top down assembly methods are currently superior
for the possibility of interconnection and integration, as in
electronic circuitry. Bottom-up assembly is very powerful in
creating identical structures with atomic precision, such as
the supramolecular functional entities in living organisms. In
many different fields of nanoscale science, e.g. the production
of semiconductor quantum dots for lasers, the production of
nanoparticles by a self organization, and the generation of
vesicles from lipids, self-organization is used for the generation
of functional nanometre-sized objects. To date, man made self-
organized structures [38] remain much simpler than natures
complex self-organized processes and structures.
As noted above, there is also no reason to believe that
processes of self-assembly, which are scientifically very im-
portant for the generation of nanoscale structures, could lead
to uncontrolled self perpetuation [36].
2) Magnetic: Magnetic nanoparticles are a class of
nanoparticles which can be manipulated by using magnetic
field gradients. Such particles commonly consist of magnetic
elements such as iron, nickel and cobalt and their chemical
compounds. While nanoparticles are smaller than 1 micrometer
in diameter (typically 5500 nanometers), the larger microbeads
are 0.5500 micrometer in diameter. Magnetic nanoparticle
clusters which are composed of a number of individual mag-
netic nanoparticles are known as magnetic nanobeads with a
diameter of 50200 nanometers [43] [44]. The physical and
chemical properties of magnetic nanoparticles largely depend
both on the synthesis method and chemical structure. In most
cases, the particles range from 1 to 100 nm in size and
may display superparamagnetism [45]. We will talk about the
quantum tunneling in the magnetic nanoparticles below.
One of the fascinating properties of magnetic nanoparticles
is the reduction from multidomains to a single domain as
the particle size reduces to some limit values. Besides the
vanishing of magnet hysteresis and the large reduction of
the coercive field for nanoparticles, the macroscopic quantum
tunneling of the magnetic moment becomes its non-analyticity
in the ground state energy of the infinite lattice system [46].
Unusual electronic and magnetic characteristics are prevalent
at nanozero temperatures such as the metal-insulator transition
in transition metal oxides [47], non-Fermi-liquid behavior of
highly correlated f-electron compounds [48] [49], abnormal
symmetry states of high-Tcsuperconducting heterostructures.
The investigation of the remarkable properties of these systems
has attracted great attention by researchers in condensed matter
physics. The physics underlying the quantum phase transitions
described above is quite involved and in many cases, has not
been completely understood so far.
A surface spin-glass layer is proven to be ubiquitous in
magnetic nanoparticles at low temperatures [50]. A larger
surface to volume ratio of the small nanoparticles implies
a stronger surface anisotropic field to frustrate and disorder
the inner spins, causing quantum tunneling at higher temper-
atures [51] [52] [53].
At a low temperature, magnetic viscosity of these systems
shows a constant value below a finite temperature reflecting
the independence of thermally over-barrier transitions and is
the signature of quantum tunneling of magnetization. However,
at high temperatures, single-domain magnetic nanoparticles
are thermally free to orient their spin directions and exhibit
superparamagnetic properties. The superparamagnetic state
is blocked as the temperature lowers down to enhance the

exchange interactions between particles.
3) Dielectric: A dielectric material, or dielectric, is an
electrical insulator that can be polarized by an applied electric
field. When a dielectric is placed in an electric field, electric
charges do not flow through the material as they do in a
conductor, but only slightly shift from their average equi-
librium positions causing dielectric polarization. As materials
considered for inclusion in nanodevices are designed for more
complex behavior, dielectric properties have become increas-
ingly important. Characterization of nonlinear properties, such
as piezoelectric, ferroelectric, and ferromagnetic responses is
now critical.
The dielectric constant, the response function of the mea-
sured external field, the displacement, to the local electric filed,
closely relates to the conductivity and optical properties of
materials. The dielectric constants of metallic nanoparticles in
microwave frequency range have rarely been reported [54].
The high microwave field absorption of the metallic particles
involves using the conventional method of inserting a powder-
pressed thin disk in a microwave guide to determine the
dielectric constant by measuring the attenuation and phase
delay of the penetrating wave, which cannot be used [55].
The electrical and magnetic properties of numerous nano-
materials are completely different from those of their bulk
counterparts. Changes in dielectric properties were attributed
to changes in particle size, shape, and boundaries [56] [57].
The modified dielectric properties were used as capacitors,
electronic memories, and optical filters. Materials exhibiting
a giant dielectric constant have already been reported else-
where [58] [59]. The high dielectric permittivity and the low
loss factors over a wide frequency range are always of a great
interest [61] [60].
Dielectric constants specify the response to the dipole
displacement in an externally applied field in terms of ion
and electron motion. Incident electromagnetic (EM) fields of
different frequencies cause different responses from ions and
electrons. As the size of the metal films or particles declines,
the mean free path becomes constrained by surface scattering.
The conductivity of metallic nanoparticles decreases as the
particle size decreases and behaves as non-conducting below
a critical size and temperatures.
The magnitude of the real part of dielectric constants for
metallic nanoparticles decreases with a decreasing particle
size [55], suggesting that the particles become less conducting
as the particle size decreases. The microwave absorption
depends on the shape and size distribution, making it ex-
tremely difficult to determine the imaginary part. The darkish
appearance of many different metallic nanoparticles illustrates
that the measured dielectric constants, even of silver and iron
nanoparticles, are close in proximity.
C. Semiconductors
A semiconductor material has an electrical conductivity
value falling between that of a conductor, such as copper, and
an insulator, such as glass. Semiconductors are the foundation
of modern electronics. Semiconducting materials exist in two
types - elemental materials and compound materials [62].
Fig. 5. Nanoscaled transistor can be fabricated by inserting nanowires
(or single molecule) between source and drain electrodes mounted on a
silicon/silicon dioxide support [63].
The transition from devices relying on collections of
molecules to unimolecular devices requires the identification of
practical methods to contact single molecules. This fascinating
objective demands the rather challenging miniaturization of
contacting electrodes to the nanoscale. A promising approach
to unimolecular devices relies on the fabrication of nanometer-
sized gaps in metallic features followed by the insertion of
individual molecules or nanomaterials between the terminals
of the gap. The strategy permits the assembly of nanoscaled
three-terminal devices equivalent to conventional transistors.
Fig. 5 shows a nanoscaled transistor which can be fabricated
by inserting nanowires.
The selected examples of tubes, wires or quantum dots in
this section only hint at the range of materials from which
nanostructures are made. The summary in Table III provides
some perspective of the diversity that is possible today.
TABLE III. NANOSTRUCTURED MATERIALS
Nano tubes Carbon, VxOy, SnO2, InAs,
GaAs, GaN, Co3O4, BN, WS2,
ZrO2, MoS2, H2Ti3O7, polypyr-
role, peptides, metallo porphyrin,
SiO2, Cu
Nano wires Si, In, InP, InAs, MgO, MoSe,
GaN, Ga2O3, ZnO, SnO2, TiO2
, Pt, Au, Ag, Ni, Cu, Bi, Co, Pb,
LiMnO2, CdTe, LiNiO2, CdS, B,
PbSe, FeCo, FeNi, CoPt, BN, ZnS,
ZnSe, CdSe, SiGe, ErSi2, DySi2,
polyanaline
Nano dots GaAs, InP, Si, InAs, CdS, CdSe,
TiO2, ZnS, Fe2O3, MnO4, Cr2O
1) Nanotubes: A nanotube is a nanometer-scale tube-like
structure. Semiconductor nanotubes are a natural candidate
for three terminal nanodevices. The nanotube is positioned to
bridge two metal electrodes, which as the source and drain of
the field-effect transistors(FETs). The silicon wafer is used as a
back gate. These devices behave as unipolar p-type FETs with
on/off current switching ratios of ∼105. However, the first
devices had a high contact resistance(>1 M Ω) which led to
a low conductance ∼10−9A/V. Subsequent improvements in
the processing result in decreases in contact resistance by three
orders of magnitude and increase conductance by two orders
of magnitude. These nanotubes were p-type. n-type nanotubes
can be made by doping[64] or annealing in a vacuum [65].

Fig. 6. Conceptual diagram of single-walled carbon nanotube (SWCNT) (A)
and multiwalled carbon nanotube (MWCNT) (B) delivery systems showing
typical dimensions of length, width, and separation distance between graphene
layers in MWCNTs [66].
Several groups have demonstrated complex devices using a
combination of tubes or tube/metal interfaces. Fig. 6 shows
a conceptual diagram of single-walled carbon nanotube and
multiwalled carbon nanotube.
It was soon learned that nanotubes have high strength
and modulus, have interesting thermal conductivity, and the
electrical properties are sensitive to surface adsorption. This
combination of properties suggests applications that range
from reinforced polymer composites, chemical sensors, field
emission displays, drug delivery devices, thermal management
systems, and SPM tips. Consequently, activity in this area has
increased dramatically. The primary challenge to use of nan-
otubes is that current synthesis processes cannot produce tubes
with predefined lengths or properties. Much effort is being
expended on finding schemes for selection and/or separation.
Although the first nanotubes were carbon based, this by no
means defines a fundamental limitation. The general appeal
of nanotubes from more complex materials has motivated
synthesis of a wide range of compounds in this geometry. This
area is growing rapidly.
Carbon is a unique light atom that can form one-, two-
, or threefold string chemical bonds. The planar threefold
configuration forms graphene planes that can, under certain
growth conditions, adopt a tubular geometry. Properties of
carbon nanotubes may change dramatically depending on
whether single-wall carbon nanotubes(SWNT) or Multiwall
Nanotubes(MWNT) are considered. We will consider several
properties of carbon nanotubes below [6].
1) Variability of carbon nanotube properties.
Properties of MWNTs are generally not much dif-
ferent from that of regular polyaromatic solids, and
variations are then mainly driven by the textural type
of MWNTs considered and the quality of the nanotex-
ture, both of which control the extent of anisotropy.
However, the properties for SWNTs may change
dramatically depending on whether single SWNT or
SWNT ropes are involved. Note that: The following
description will emphasize SWNT properties, as far
as their original structure often leads to original
properties with respect to that of regular polyaromatic
solids.
2) General properties.
SWNT-type carbon nanotube diameters fall in the
nanometer range and can be hundreds of micrometers
long. SWNTs are narrower in diameter than the
thinnest line able to be obtained by electron beam
lithography. While the length of SWNTs can be
macroscopic, the diameter has a molecular dimen-
sion. As a molecule, properties are closely influenced
by the way atoms are displayed along the molecule
direction. The physical and chemical behaviors of
SWNTs are therefore related to their unique structural
features.
3) SWNT adsorption properties.
The very high surface area, as we talked about before,
yields many interesting features. Theoretical calcula-
tions have predicted that the molecule adsorption on
the surface or inside of nanotube bundle is stronger
than that on an individual tube.
a) Accessible SWNT Surface [67] [68] [69].
b) Adsorption Sites and Binding Energy of the
Adsorbates [70] [71]
4) Transport properties.
The narrow diameter of SWNTs has a strong in-
fluence on its electronic excitation due to its small
size compared to the characteristic length scale of
low energy electronic excitation. Combined with the
particular shape of the electronic band structure of
graphene, carbon nanotubes are ideal quantum wires.
5) Mechanical properties.
While tubular nano-morphology is also observed for
many two-dimensional solids, carbon nanotubes are
unique through the particularly strong three-folded
bonding of curved graphene sheet, which is stronger
than in diamond as revealed by their difference in
C–C bond length. This makes carbon nanotubes –
SWNTs or c-MWNTs – particular stable against
deformations.
6) Reactivity.
The chemical reactivity of graphite, fullerenes, and
carbon nanotubes exhibits some common features.
Like any small object, carbon nanotubes have a
large surface with which they can interact with their
environment. It is worth noting, however, that the
chemistry of nanotubes differs from that of regu-
lar polyaromatic carbon materials because of their
unique shape, small diameter, and structural proper-
ties.
Those above properties make nanotubes much more suit-
able to nanosemiconductors circuits compared with CMOS
circuits.
2) Nanowires: Nanotubes of the length longer than 1
µm are usually called nanowires or nanofibers. Nanowires
are especially attractive for nanoscience studies as well as
for nanotechnology applications. They can be prepared by
physics, chemistry or the mixture to produce metallic wires,
and semiconductors [72] [73]. Nanowires, compared to other
low dimensional systems, have two quantum confined direc-
tions while still leaving one unconfined direction for electrical
conduction. This allows them to be used in applications which
require electrical conduction, rather than tunneling transport.
Because of their unique density of electronic states, nanowires

in the limit of small diameters are expected to exhibit sig-
nificantly different optical, electrical, and magnetic properties
from their bulk 3D crystalline counterparts.
Increased surface areas, very high density of electronic
states and joint density of states near the energies of their
van Hove singularities, enhanced excitation binding energy,
diameter-dependent bandgap, and increased surface scattering
for electrons and phonons are just some of the ways in which
nanowires differ from their corresponding bulk materials. Yet
the sizes of nanowires are typically large enough(>1 nm in the
quantum confined direction) to have local crystal structures
closely related to their parent materials, thereby allowing
theoretical predictions about their properties [6].
Due to the enhanced surface-to-volume ratio in nanowires,
their properties may depend sensitively on their surface con-
dition and geometrical configuration. Even nanowires made
of the same material may possess dissimilar properties due
to differences in their crystal phase, crystalline size, surface
conditions, and aspect ratios, which depend on the synthesis
methods and conditions used in their preparation. Below are
listed several novel properties of nanowires.
1) Transport Properties
The study of nanowire electrical transport properties
is important for nanowire characterization, electronic
device applications, and investigation of unusual
transport phenomena arising from one-dimensional
quantum effects. Important factors that determine the
transport properties of nanowires include the wire
diameter, material composition, surface conditions,
crystal quality, and the crystallographic orientation of
the wire axis, which is important for materials with
anisotropic materials parameters, such as the effective
mass tensor, the Fermi surface, or the carrier mobility.
Electronic transport phenomena in low-dimensional
systems can be roughly divided into two categories:
ballistic and diffusive transport. Ballistic transport
phenomena occur when electrons travel across the
nanowire without any scattering; however, the trans-
port is in the diffusive regime, and the conduction
is dominated by carrier scattering within the wires
due to phonons, boundary scattering, lattice and other
structural defects, and impurity atoms.
a). Conduction Quantization in Metallic Nanowires:
The phenomenon of conductance quantization occurs
when the diameter of the nanowire is comparable to
the electron Fermi wavelength, which is on the order
of 0.5 nm for most metals [74]. Most conductance
quantization experiments up to the present have been
performed by joining and separating two metal elec-
trodes.
b). Diameter-dependent Properties of Semiconductor
Nanowires:
The electronic transport behavior of nanowires may
be categorized based on the relative magnitude of
three length scales: carrier means free path, the de
Broglie wavelength of electrons and wire diameter.
For different relations among the three length scales,
nanowires exhibit different transport properties and
show some extend diameter-dependent properties [6].
Transport properties of nanowires in the classic finite
size and quantum size regimes are highly diameter-
dependent.
c). Thermoelectric Properties:
Nanowires are predicted to be promising for thermo-
electric applications [75] [76], due to their novel band
structure compared to their bulk counterparts and the
expected reduction in thermal conductivity associated
with enhanced boundary scattering. Due to the sharp
density of states at the 1D subband edges, nanowires
are expected to exhibit enhanced Seebeck coefficients
compared to their bulk counterparts.
d). Thermal Conductivity of Nanowires:
The thermal conductivity of small homogeneous
nanowires may be more than one order of magnitude
smaller than in the bulk, arising mainly from strong
boundary scattering effects [77]. And, phonon con-
finement effects may eventually become important at
still smaller diameter nanowires.
2) Optical Properties
Optical methods provide an easy and sensitive tool
for measuring the electronic structure of nanowires
since optical measurements require minimal sample
preparation and the measurements are sensitive to
quantum effects.
Phonons in nanowires are spatially confined by the
nanowire cross-sectional area, crystalline boundaries
and surface disorder. These finite size effects give
rise to phonon confinement, causing an uncertainty
in the phonon wave vector, which typically gives rise
to a frequency shift and a lineshape broadening. Since
zone center phonons tend to correspond to maxima
in the phonon dispersion curves, the inclusion of
contributions from a broader range of phonon wave
vectors results in both a downshift in frequency and
an asymmetric broadening of the Raman line that
develops a low-frequency tail.
3) Quantum Dots: The study of quantum dots (QD) has a
longer history, arising as it does out of the semiconductor field
of quantum wells, heterostructures, low dimensional electron
gasses, etc [20]. Semiconductor quantum dots with tunable
optical emission frequencies due to the quantum size confine-
ment present the utmost challenge and point of culmination
of semiconductor physics. A modified Stranski-Krastanow
growth method driven by self-organization phenomena at the
surface of strongly strained heterostructure driven has been
realized [78].
Quantum dots can be many things theoretically, but the ini-
tial products that incorporate quantum dots are small grains (a
few nanometers in size) of semiconductor materials [79] [80].
These grains are stabilized against hydrolysis and aggregation
by coating with a layer of zinc oxide and a film of organic
surfactant, technologies already familiar to the chemical indus-
try in making paints and washing powders. These first semi-
conductor quantum dots are fluorescent – they emit colored
light when exposed to ultraviolet excitation – and are being
tested in displays for computers and mobile telephones, and
as inks. These materials are interesting for several reasons:
one is that they do not photobleach(that is losing their color
on exposure to light); a second is that a single manufacturing
process can make them in a range of sizes, and thus, in a single
process, in all colors. Their applications in biology illustrate

the difficulties in introducing a new technology [8].
All semiconductor devices incorporate a crucial ingredient
for their proper functioning. The great interest in understanding
the properties of these impurity containing systems comes
from the fact that the impurity modifies the energy levels of
the materials and in turn affects their electronic and optical
properties [81] [82]. Thus, these systems have potential use
in electro-optical devices [83]. A consequence of the strong
confinement of the impurity states in quantum dots is that
their electronic structures collapse to a series of discrete levels,
contrary to the continuous source and drain associated with
bulk semiconductors, or to their higher dimensional neighbors
such as quantum wells and quantum wires [84].
The study of bound impurity states in such structures
is recently considered to be a subject of fundamental in-
terest [85] [86] [87] [88]. There are ample investigations
that highlight the influence of the mechanism and control of
dopant incorporation, as well as impurity location in char-
acterizing several properties of the quantum dots of nan-
odevices [89] [90] [91]. The effects of impurity need to
be accessed on structure, electron density, and information
entropy, etc., in case device level applications based on dot
atoms are envisaged.
It needs to be mentioned that quantum dots are now
realizable in various shapes and sizes and device applications.
As the physical dimensions of the dot approach the nanometer
scale, size effects begin to play an important role, leading to
drastic changes in measured properties [92]. As fabrication
processes improve, control of dot size is enhanced. In the
last few years, semiconductor quantum dots with tunable size
have attracted a great deal of attention, particularly in the
1.3∼1.55 µm range of optical communications [93] [94]. The
location of the impurity center together with confining fields
could create a geometry where the dot size would display
significant sensitivity in modulating the energy levels. Such an
isolated impurity (electron-type) doped quantum dot structure
could be a test case serving as representative of experimentally
realizable ones.
Researchers and scientists are interested in the nanoscale,
because when many materials get down to these tiny sizes,
they start to behave differently and novel properties emerge.
Sometimes the material becomes explosive or its melting
point changes or a new property is revealed. These novel
properties are mostly due to changes in size and scale and
the physics rules that govern materials at the nanoscale. Many
novel properties are emerging as materials are being reduced
from macroscale to nanoscale. This change in the properties
of materials is leading to the creation of new and enhanced
nanomaterials. Nanoscale materials like nanoparticles and
nanofibres have an exciting future in a wide range of high-
tech applications.
IV. NANODEVICES
A major issue in nanoscale research is how the scientific
paradigm changes will be translated and implemented into
novel technological processes. Nanoparticle systems, including
nano-clusters, nanotubes, nanostructured particles, and other
three-dimensional nanostructures in the size range between 1
and 100 nm are usually seen as the tailored precursors for
nanostructures materials and corresponding nanodevices.
Different application areas together promote the devel-
opment of nanodevices, such as information and commu-
nication technologies, automotive, aerospace, energy, medi-
cal/pharmaceutical, chemicals and advanced materials, textiles
etc. In this paper, we mainly focus on the various nano-
transistors and nanosensors used in computation and informa-
tion storage and transmission areas.
A. MOS Transistors
The ever progressing and seemingly unstoppable minia-
turization of MOS (Metal Oxide Semiconductor) transistors
becomes the essential factor responsible for the continuous
progress of nanotechnology. MOS transistors with channel
lengths of around 100 nm have already been introduced in lots
of semiconducting areas, such as the production of memory
modules and microprocessors. Now newly developed silicon
transistors with the channel length down to 18 nm have
been popularly used in the fabrications of MOS technology,
according to the ITRS surveys [95].
However, MOS technology is not just miniaturizing the size
of transistors and special processes are needed to accomplish
the transition from micrometer scale to the nanometer regime.
Following are the essential process steps for transition [96]
•Adjustment of the gate oxide thickness to a few
nanometers.
•Reduction of the doping depths to a few nanometers.
•Optimization of the spacer width and of the LDD
(Lightly Doped Drain) doping.
•Optimization of the channel doping.
•Introduction of special implantation (such as pocket
implantation).
For transistors with the channel lengths below 100 nm,
parasitic short channel effects become increasingly dominant
and are difficult to reduce with the usual countermeasures.
Therefore, measures for transitions, such as a further reduction
of the gate oxide thickness or the decrease of all doping
depths, are both technologically and physically limited for
mass fabrications.
While the electrical characteristics of MOS transistors such
as slop and switching speeds have been improved largely in
the recent years by the progressive reduction of the transistor
dimensions regarding current manufacturing technologies, a
rather opposite trend is to be expected for the sub-100 nm
transistors. However, dynamic investigations show a trend that
the switching speed of sub-100 nm MOS transistors does not
increase by the amount that is generally expected. The possible
reasons are partly due to the increasing doping gradients which
lead to increasing parasitic capacitance of transistors. Analyses
by a large number of independent scientists show, however,
that in the future the delay time in the signal lines of the
microchip will be one of the dominate effects on the electrical
characteristics and hence the switching times of the transistors
were not need to be given much attention anymore, contrary
to today’s conditions [97].
Besides the electrical characteristics changes, the quantum
effects in MOS devices observed so far are relevant only for

Fig. 7. Junction section of NPN bipolar transistor [98].
very low-temperature operation. It is still unknown whether
further quantum effects occur below 30 nm channel lengths.
B. Bipolar Transistors [96]
The bipolar technology of transistors uses structures with
nanometer dimensions only during the self-adjusting bipolar
process. Due to the self-adjustment or self-assembly of the
dopings relative to each other, the transit frequencies of bipolar
integrated circuit technology could be enabled in the range
above 40 GHz for pure silicon transistors and up to about
120 GHz for Silicon-Germanium(SiGe) switching elements.
From the production aspects, extremely thin epitaxial films
of different doping levels are used as the collector(100 nm)
and base layers(<50 nm) instead of implantation or diffusion.
And, only the emitter is diffused from polysilicon layer into
the crystal. Fig. 7 shows the junction section of NPN bipolar
transistor.
The self-adjusting bipolar process is characterized by high
critical frequencies(>40 GHz) of the circuit elements in con-
nection with a relatively high packing density. The typical area
of the emitter amounts to about 0.15 ·1.5 µm2in size. Also,
the critical frequencies for further increases could be possible
with a base layer from a heteroepitaxially grown crystalline
silicon-germanium epitaxial layer which is deposited on a sili-
con substrate with the molecular beam epitaxy or via MOCVD
(Metalorganic Chemical Vapor Deposition) procedure [99].
Since many typical applications of the bipolar transistors
in the high critical frequency regime are taken over today by
MOS transistors, the fields of application of these elements in
the future are exclusively used within the very high-frequency
regime. And the heterojunction bipolar transistors from SiGe
are particularly suitable for this purpose. The nanostructuring
of bipolar transistors will also lead to a further increase in the
critical frequencies, but no substantial technological innovation
is to be expected in this area yet [96].
C. Single Electron Transistors
The single electron transistor (SET) can be as an example
of an electronic semiconductor device where a final limit of
electronics has already been reached: the switching option of a
current carried by just on the electron. The operating principle
of SET can be more easily understood with the help of Fig. 8.
To further reduce the size of current devices beyond the
limit of a hundred nanometers, the metal single electron
transistor, using the Coulomb blocked effect, has been recently
developed. The scaling of such nanosized devices down to
atomic scaling can be expected to replace the customary
semiconductor logic or analog devices. Due to the narrowing
Fig. 8. Schematic representation of the double barrier structure of a single
electron transistor [100].
of the distance down to several nanometers between isolated
electrodes such as the drain and source, the tunneling current
readily surmounts conventional conduction currents. Thus, the
tunneling of a single electron to the nanosized gate can build
a high potential drop on account of the extremely smallness
of the capacitance of the gate. Several constraints that limit
the size of SET arise from the physical principles and device
structure.
Many excellent reviews on the SET transis-
tor [101] [102] [103] have been reported. In electron-beam
lithography, the well-known proximity effect refers to
variation in the width of patterned lines with the density of
other shapes nearby, which this type variation, of course,
makes increasing the resolution more difficult. Therefore, the
electron proximity effect has been one of the major obstacles
to achieving fine resolution in electron beam lithography. The
distribution of intensity of exposure has a Gaussian intensity
profile, because electrons are both forward scattered and back
scattered. It can be partly compensated for the proximity
effects by adjusting the dosage of electron beams according
to the density of the patterns, or to anticipate the changes
in dimensions of the features and then make compensating
adjustments in advance.
In SETs, the nano-constriction between the source (or
drain) electrode and the quantum dot of the Si-SET was
formed by overlapping the distribution of the electron dosages
of two separately written nano-dots performing on a silicon
oxide insulating (SOI) wafer [101]. Also, bi-directional pump
current, as well as single electrons transport, can be observed
in the silicon dual-gate bi-directional electron pumps. The
quantized current has been observed in a silicone dual-gate
bi-directional electron pump. The polarity of the pump current
can be altered either by the phase difference of the AC
modulations added to the gate voltages [103], or by the DC
voltages applied to the two gate electrodes.
D. Carbon Nanotube Transistors
As demonstrated in Section III, carbon nanotubes are made
out of a structured network with the basic unit being six carbon
atoms in the ring configuration and arranged in the form of
cylinders. The electronic structure of the carbon nanotubes
critically depends on its geometry of the interconnection
between the carbon rings, resulting either in metallic or in
semiconducting behavior [105].
The particular interest in this new materials is due to
reports of very low specific resistivities for metallic carbon

nanotubes [104] and on high hole mobilities for semicon-
ducting nanotubes [105] [106]. Those interesting electronic
properties can be physically explained by the low density of the
surface state. The material forms a two-dimensional network
of carbon atoms without the presence of dangling bonds. When
assembling in cylindrical form, the problem of the usually
enhanced recombination at the edges of the semiconductor can
be avoided [105].
The small device dimensions in semiconducting carbon
nanotubes together with the high values of the charge carrier
mobilities make CNT-based devices very interesting for micro-
electronic applications. So far field-effect type transistors have
mostly been implemented [107] [108] [109] because carbon
nanotubes exhibit very high hole mobilities in particular. It
should, however, also be mentioned that first experiments to
realize a bipolar p-n-p transistor were successful using CNTs
transistors [110].
One of the main problems regarding the fabrication of
integrated circuits using CNT transistors is the limited re-
producibility of the CNT growth process. An alternative ap-
proach to lateral integration is that manufacturing of arrays
of CNTs based on vertical structures. Very homogeneous and
reproducible growth of vertical CNT arrays by pyrolysis of
acetylene on cobalt coated alumina substrates has already been
reported [111].
As a perspective for other applications of carbon nanotubes
for electronic devices, it should be mentioned that heterojunc-
tions between CNTs and silicon quantum wires have already
been reported [112]. In this case, the silicon quantum wires are
grown by CVD (Chemical Vapor Deposition) [99] deposition
in a silane atmosphere selectively on top of the CNTs. They
consist of a crystalline core covered by a thin amorphous
silicon layer and a SiO2layer respectively. The electrical
characterization of this heterostructure shows a behavior very
similar to a Schottky diode and the current-voltage character-
istics clearly exhibited rectifying behavior [113].
E. Memristor
Recent discovery of the memristor has sparked a new wave
of enthusiasm and optimism in revolutionizing circuit design,
marking a new era for the advancement of neuromorphic
and analog applications. Leon Chua conceived the need for
an additional fundamental circuit component in addition to
the resistor, capacitor, and inductor [114]. Chua reasoned the
existence of a missing circuit element from symmetry reasons,
by looking at the six possible combinations of the relationships
of four fundamental circuit variables - the voltage V, current
I, flux ϕ, and electric charge q. While the charge is the
integral upon the time of the current and the flux is integral
upon the time of the voltage, the other possible relationships
are connected by two-terminal circuit components. Resistors
connect voltage to current by Ohm’s law (V=IR), capacitors
connect charge to voltage (q=CV ), and inductors connect
current to flux (ϕ=LI). The sixth possible relationship is
the connection between charge and flux and is not covered by
any conventional circuit element. Chua reasoned, for the sake
of completeness, the existence of a fourth fundamental circuit
element that connects the charge and flux and named the device
the memristor, as a short for ‘memory resistor’. The six
combinations of the relationships are illustrated in Fig. 9.
Fig. 9. Illustration of the six combinations of the relationships between
voltage v, charge q, flux ϕ, and current i. The memristor connects the charge
and flux. [115]
The beauty of the memristor lies in its ability to remember
its history state via the modulation of the internal state vari-
ables of the device. This memory capability is precisely what
excites the electronics community and the underlying reason
for the memristors revolutionary effects in circuit design.
And, as CMOS technologies are approaching the nanoscale
floor, Moores Law will eventually cease to exist, with devices
attaining comparable dimensions to their constituting atoms.
Thus, the focus has to be shifted to finding new devices which
are increasingly infinitesimal and equally if not more capable
than transistors.
The memristor is a type of non-volatile memory. Digital
applications usually require devices that combine long reten-
tion times with fast write speeds. The memristor can in practice
achieve a long state lifetime (≥107) and ultra-fast switching
speed, since relatively small biases can increase the switching
speed up to six orders of magnitude due to the highly non-
linear rate of switching. Additionally, the memristors’ ability
to maintain a state, without requiring external biasing, can
significantly reduce the overall power consumption, while its
deep nanoscale physical dimensions make the memristor (min-
imum reported: 5 x 5nm) an ideal candidate for implementing
ultra-high-density memories, thus providing a much-needed
extension to Moores law. As a consequence, memristors are
often promoted as an emerging bi-stable switch for resistive
random-access memory(RRAM).
Clearly, the characteristics of the scalability, the low power
consumption and the dynamic response for the memristor are
attributes that make this device attractive for a number of ap-
plications, from non-volatile memory [116] to programmable
logic [117]. Particular emphasis is however given to the non-
linear nature of memristor that resembles the behavior of
chemical synapses [118] [119], thus, marking a new era for
neuromorphic engineering. Memristors can be used in many
applications, such as memory, logic, analog circuits, and neu-
romorphic systems. Also, memristors offer several outstanding
advantages as compared to standard memory technologies:
good scalability, non-volatility, effectively no leakage current,
and compatibility with CMOS technology, both electrically and
in terms of manufacturing [120].

Although the device can be implemented as a bi-stable
switch, its operation is not limited by discrete states, since
a continuous memristive spectrum is attainable, signifying the
potential employment of memristors as purely analog memory
elements. Meanwhile, the memristance of a device can be
varied in a very controlled manner by appropriate biasing
operations. This property can be particularly useful in non-
volatile memory applications where arbitrary signals can be
utilized to program the conductance of device at multiple
levels, thus increasing the memory capacity without increasing
the number of elements [121].
F. PCM
Over the past four decades, silicon technology has enabled
data storage through charge retention on metal-oxide-silicon
(MOS) capacitive structures. However, as silicon devices are
continuously scaled toward (sub-) 10 nm dimensions, minute
capacitors become very leaky by simple quantum mechanical
considerations, thus the memory storage density appears to
plateau. Phase Change Memory(PCM) is an emerging tech-
nology which combines the unique properties of phase change
materials with the potential for novel memory devices, which
can further help lead to the new computer architectures.
Phase change materials store information in their amorphous
and crystalline phases respectively, which can be reversibly
switched by the applying an external voltage [122].
Phase change materials exist in an amorphous and one or
sometimes several crystalline phases, and they can be rapidly
and repeatedly switched between these phases by external acti-
vation, such as voltage. The switching can be typically induced
by heating through optical pulses or electrical (Joule) heating.
The optical and electronic properties can vary significantly
between the amorphous and crystalline phases, and this combi-
nation of optical and electrical contrast and repeated switching
allows data storage. Today, many technologically useful phase
change materials are chalcogenides, which owe their success
in this regard to a unique combination of properties, which
may include strong optical and electrical contrast, fast crystal-
lization, and high crystallization temperature (typically several
hundred degrees Celsius). Fig. 10 shows the general principles
of phase change memory.
PCM mainly based on the repeated switching activities
of phase change material between the amorphous and the
crystalline states associated with a large change in resistance.
Data information is stored in the phase of the material and is
read by measuring the resistance of the PCM cell, meanwhile,
the cell is programmed and read using electrical pulses [122].
Phase change materials are at the heart of PCM technology,
and their corresponding properties to a large extent determine
its functionality and success. However, optimization of phase
change materials is not only application specific but also
technology node specific. For example, the threshold voltage is
on the order of 1 V in current typical PCM cells, but if devices
are scaled to much smaller dimensions, the threshold voltage
scales with the size of the amorphous region, and for very
small cells, it could become comparable to the read voltage
such that every read operation could alter the cell state [122].
Using PCM to replace DRAM is a formidable challenge,
it is because very fast switching times in the nanoseconds
Fig. 10. Principle of phase change memory. Starting from the amorphous
phase with large resistance R, a current pulse is applied. At the threshold
voltage VT, the resistance drops suddenly, and a large current (I) flows that
heats the material above the crystallization temperature Txfor a sufficiently
long time to crystallize (set operation). In the crystalline state, the resistance
is low. A larger, short current pulse is applied to heat the material above the
melting temperature Tm. The material is melt-quenched and returns to the
amorphous, high resistance state (reset operation). In the schematic, different
colors represent different atoms (such as Ge, Sb, and Te in the commonly
used GeSbTe compounds) in the phase change materials. [122].
range and extremely high cycle numbers of ∼1016 present
a combination of requirements that have not been achieved
by phase change materials nowadays. Also, DRAM replace-
ment with PCM is a special case since DRAM is a volatile
memory, whereas PCM is a non-volatile memory. They are not
comparable. If PCM were to achieve DRAM-like performance,
it would open up new possibilities to realize completely
new computer architectures. Very fast switching times have
been achieved for several phase change materials, including
Ge2Sb2T e5[123] [124] and GeTe [125] in actual PCM
devices. However, the high cycle number remains an enormous
challenge, and it appears that scaling to smaller dimensions of
the phase change material is beneficial for cycling in some
extent.
PCM cells cannot only be programmed in the on- or off-
state, it can also be possible to reach intermediate resistance
states. Up to 16 levels have been demonstrated using a write-
and-verify scheme [126]. A continuous transition can be uti-
lized between resistance levels in PCM devices in an analog
manner, this effect can be used to program them to mimic the
behavior of a synapse, for example. Such an attempt could
lead to the design of a neuromorphic computer with electronic
hardware that resembles the functions of brain elements, such
as the neurons and synapses. The phenomenon of spike-
timing-dependent plasticity (a biological process where the
strength of connections between neurons are adjusted during
learning) could be demonstrated in PCM devices using specific
programming schemes [127] [128]. Image recognition using
a neural network of PCM devices has also been demon-
strated [129] [130] [131]. These could potentially lead to
a compact and low power neuromorphic computing system
that is capable of processing information through learning,
adaptation, and probabilistic association like the brain [122].
G. Nanosensors
One of the early applications of nanotechnology is in the
field of nanosensors [132] [133] [134] [135]. A nanosensor
is not necessarily a device merely reduced in size to a few
nanometers, but a device that makes use of the unique proper-
ties of nanoparticles and nanomaterials to detect and measure

Fig. 11. An integrated nanosensor device. [138].
new types of events appeared in the nanoscale [136]. However,
there are no general rules about nanosensors with regards
to their unique properties. Most reviews on nanosensors are
focused on the particular type of sensors, such as biological
nanosensors, optical nanosensors, and magnetic nanosensors,
with many technical details involved. Here we present an
overview of all nanosensors, showing similarities and funda-
mental differences among the various categories [137].
In most cases, nanosensors work together and need to
communicate. Communication among nanosensors will expand
the capabilities and applications of individual nano-devices
both in terms of complexity and the range of operation.
Each sensor has its sensing range technically. The detection
range of existing nanosensors requires them to be inside the
phenomenon that is being measured, and the area covered by
a single nanosensor must be limited to its close sensing envi-
ronment. However, a network of nanosensors can cover much
larger areas and, with communication mechanism among them,
perform additional in-network processing abilities. In addition,
several existing nanoscale sensing technologies require the use
of external excitation and measurement equipment to operate.
Wireless communication between nanosensors and micro- and
macro- devices will eliminate this need [136]. In this part, we
mainly focus on nano-electromagnetic communication units to
illustrate the general principles of nanosensors.
The nanosensors are as an integrated device around
10∼100 µm in size and able to do simple tasks besides sensing
tasks, such as simple computation or even local actuation. The
internal abstract architecture of a nanosensor device is shown
in Fig. 11. In the abstract architecture, several important parts
integrate a workable nanosensor device, such as sensing unit,
actuation unit, power unit, a processing unit, storage unit, as
well as a communication unit.
1. Sensing Unit
Novel nanomaterials such as graphene and its deriva-
tives, namely, Graphene Nanoribbons (GNRs) and Carbon
Nanotubes (CNTs), provide outstanding sensing capabilities
and are the basis for many types of sensors. Based on the
nature of the different measured magnitudes, nanosensors can
be classified as shown in Fig. 12. Fig. 12 shows the types
of state-of-the-art nanosensors, physical nanosensor, chemical
nanosensor and biological nanosensor respectively, and their
corresponding measure magnitudes.
2. Actuation Unit
An actuation unit will allow nanosensors to interact with
Fig. 12. Types of nanosensors. [136].
their own close environment and can stimulate the simula-
tion. Several nanoactuators have already been designed and
implemented so far with outstanding actuation ability [135].
They can be classified as two types: Physical nanoactua-
tors [135] [139], and Chemical and biological nanoactua-
tors [140] [141].
However, the area of nanoactuators is at a very early stage
compared with nanosensors technology. The main research
challenge, besides the design and fabrication of the actuation
unit, is how to precisely control and drive the nanoactua-
tor and get the correct responses. The majority of potential
applications of state-of-the-art nanosensors are used in the
biomedical field; therefore, accuracy is one of the fundamental
requirements for nanoactuators [136].
3. Power Unit
As an integrated device, the power unit is used to provide
energy supply for the whole nanosensor. A major effort has
been undertaken to reduce existing power sources to the
microscale and the nanoscale. Nanomaterials can be used to
manufacture nanobatteries with the outstanding advantages,
such as high power density, reasonable lifetime and con-
tained charge/discharge rates. However, having to periodically
recharge them limits the usefulness of nanobatteries in realistic
nanosensors applications and new technology is needed to
overcome the power issues.
In order to overcome the limitations of nanobatteries,
the concept of self-powered nanodevices has been recently
introduced in [142] [143]. The working principle of these self-
powered devices is based on the conversion of the following
types of energy into electrical energy which could power
nanosensors:
•Mechanical energy: produced for example by the hu-
man body movements, or muscle stretching.
•V ibrational energy :generated by acoustic waves or
structural vibrations of buildings, among others.
•Hydraulic energy: produced by body fluids, or the blood
flow.
4. Processing Unit
Nanoscale processors are being enabled by the develop-
ment of tinier FET transistors in different forms. Nanomateri-
als, such as CNTs and GNRs, can be used to build transistors
in the range of nanometer scale [144]. The small size of
nanosensor devices will limit the number of transistors in

nanoscale processors, limiting the complexity of the operations
that these will be able to do, but not the speed at which nano-
processors will be able to operate [145].
Independent of the specific approach followed to design
these nano-transistors, one of the main challenges is in in-
tegrating them in future processor architectures. Although the
experimental testing of individual transistors has been success-
fully conducted in literature, simple processing architectures
based on these nano-transistors are still being investigated and,
so far, the future processor architectures based on CNTs and
graphene still need to be defined clearly before getting the
actual prototypes.
5. Storage Unit
Ideally, nano-memories utilizing a single atom to store
a single bit are being enabled by nanomaterials and new
manufacturing processes [146] [147]. Several research chal-
lenges for nano-memories are summarized in twofold. First,
for the time being, existing nanoscale memories require much
more complex and expensive machinery to be written. Being
able to read and write these memories in the nanoscale will
be necessary for programmable nanosensor devices. Second,
similarly to nano-processors, one of the main challenges is to
mass manufacture compact nano-memories beyond simplified
laboratory prototypes.
6. Communication Unit
Electromagnetic communication among nanosensors will
be enabled and enhanced by the development of nano-antennas
and the corresponding electromagnetic transceiver.
•Nano-antennas
When the antenna of a classical sensor device is reduced
down to a few hundreds of nanometers, it would definitely
require the use of extremely high operating frequencies, com-
promising the feasibility of electromagnetic wireless com-
munication among nanosensor devices. However, the use of
graphene as the material to fabricate nano-antennas can over-
come this limitation. Indeed, the wave propagation velocity in
CNTs and GNRs can be up to one hundred times below the
speed of light in vacuum mainly depending on the structure
geometry, temperature and Fermi energy [148]. Thus, the
resonant frequency of nano-antennas based on graphene can
be up to two orders of magnitude below that of nano-antennas
built with non-carbon materials, so that the wave propagation
velocity can be significantly improved.
•EM Nano-transceivers
The EM (Embedded) transceiver of nanosensor device,
embedded the necessary circuitry, can perform the baseband
processing, frequency conversion, filtering, and power ampli-
fication, of the signals that have to be transmitted or that
have been received from the free-space through the nano-
antenna. Taking into account that the envisioned nano-antennas
will resonate at frequencies in the terahertz band, RF FET
transistors able to operate at these very high frequencies are
necessary [149] [150].
The applications of wireless nanosensor networks can be
classified into four main groups: biomedical, environmen-
tal, industrial, and military applications respectively. Wireless
nanosensor networks will have a great impact in almost every
field of our society, ranging from healthcare to homeland
security and environmental protection. However, enabling the
communication among nanosensors is still an unsolved chal-
lenge in nanotechnology areas.
V. DISCUSSIONS
Nanotechnologies have added new capabilities to the state-
of-the-art technologies and are projected to be commercially
available in the near future. In the above sections, we have
investigated these new properties and the implications of
the new capabilities in the nano era. This combination of
materials, physicals, semiconductors that are commonly used
in nanodevices, are a disruptive technology, changing the way
lives are organized today. In this part, we will discuss several
problems related nanotechnology, and follow with a potential
prediction based on current developments.
A. Problems with Nanotechnology
When a new technology appeared, it usually sparks con-
flicts between those wishing to exploit it as rapidly as pos-
sible and those wishing to wait–forever, if necessary–to have
it proved absolutely safe. Nanotechnology is relatively new
compared with other technologies; although parts of it are quite
familiar now, parts are unfamiliar, and it is not a surprise that
the public is wary of its potential for harm, as well as excited
by its potential for good [8].
1) Uncontrollability: Nanotechnology has changed and
will continue to change our vision, expectations, and abil-
ities to control the materials world. These developments in
nanoscale will definitely affect the physical and chemical
properties of materials. Recent major achievements include the
ability to observe structure at its atomic level and measure the
strength and hardness of microscopic and nanoscopic phases
of composite materials.
However, one concern is that nanotechnology could go
out of control if it is not correctly used. This concern is
based on an idea put forward by several futurists (Drexler,
Joy, and others) [151] [152], and adopted gleefully by science
fiction writers [153]: that is, the idea of small machines that
can replicate themselves automatically (“assemblers) and that
escape from the laboratory and eat the earth. Any statement
about the future is, of course, always personal opinion. But
there is no way that such devices can exist on earth. The idea
of small, self-replicating machines does not seem impossible
now - after all, bacteria exist - but developing such machines
de novo - a task close to developing a new form of life - has
seemed to the public to be intractably difficult; it continues
to seem so. Self-replicating nanomachines that resemble the
larger machines with which we are familiar can be built. So,
this type of concern can be dismissed, at least until and unless
scientific inventions - in self-replication, and in artificial life -
appear that will far exceed nanoscience in their importance [8].
A promising and special direction of research in the field of
nanoelectronic devices is to create storage devices having super
high density and terabit capacity using nanomaterials. The idea
that such storage devices can be created appeared soon after
STM (STMicroelectronics) capable of manipulating separate
atoms has been developed. To meet the requirements of this

type storage, the concept of using self-organizing ordered
atomic molecular structures as a storage medium has been
put forward [154]. Some progress for this type storage has
achieved. Ordered structures of organosilicon compounds on
graphite substrates have been tested, and the possibility of
recording memory elements of size 0.5 nm have been demon-
strated. However, the uncontrollability of the STM probe tip at
the atomic level and the limited set of substrates allowing work
under normal conditions have yielded no way of going beyond
separate successful experiments. Moreover, work performed
under conditions of super-high vacuum on atomically clean
surfaces have shown that carrying separate atoms from a
substrate to a probe or from a probe onto a substrate is far
from being simple enough to be achieved using state-of-the-
art technologies. These processes are of probabilistic character
with characteristic times at the level of several to tens of
milliseconds, so the necessity for normal storage operation
recording validity at level 105−106is out of the question
at the present stage.
2) Health: It found that most nanotechnologies pose no
new risks to humans or the environment. However, much
more work need to be done before research can say how
dangerous these nanoparticles could be. For example, it is
unclear that nanoparticles would do if they entered the human
body. Micrometer-sized clumps of nanoparticles, for example,
are relatively unreactive because their surface areas are smaller
than that of the same number of individual nanoparticles, and
they are too large to enter the blood stream when breathed in.
But individual nanoparticles can pass from the lungs into the
bloodstream, and are more reactive [155].
Another issue is the unknown toxicity of materials to
health. Materials can behave quite differently at the nanoscale
to the way they do in bulk. This is both because the small
size of the particles dramatically increases surface area and
therefore reactivity, and also because quantum effects start to
become significant. This potential difference is just what makes
them interesting to scientists and engineers. However, it also
means that their toxicity may be different from that of the same
chemical in the form of larger particles [156] [157]. There are
examples where nanoparticles can produce toxic effects even if
the bulk substance is nonpoisonous. This arises partly because
they have increased surface area and also because, should the
nanoparticles enter the body through inhalation, ingestion, or
absorption through the skin, they are able to move around and
enter cells more easily than larger particles.
Little research has been carried out on the toxicity of
manufactured nanoparticles and nanotubes, but we can learn
from studies on the effects of exposure to mineral dust in
some workplaces and to the nanoparticles in air pollution.
Considerable evidence from industrial exposure to mineral dust
demonstrates that the toxic hazard is related to the surface
area of the inhaled particles and to their surface activity.
Epidemiological studies of urban air pollution support the
conclusion that finer particles cause more harm than coarser
ones diesel P M10 pollution is implicated in heart and
lung disease and asthma, particularly in susceptible people.
Although we breathe in millions of pollutant particles with
each breath, apparently without serious harm, increases of only
10 µg/m3are consistently associated with a 1% increase in
cardiac deaths.
It is very unlikely that new, manufactured nanoparticles
could be introduced into humans in doses sufficient to cause
the health effects that have been associated with air pollution.
However, some may be inhaled in certain workplaces in
significant amounts and steps should be taken to minimize
exposure. Toxicological studies have investigated nanoparticles
of low solubility and surface activity. Newer particles with
characteristics that differ substantially from these should be
treated with particular caution.
Long, thin fibers like asbestos (narrower than about 3
µm and longer than about 15 µm) are a particular cause
for concern [158]. They have aerodynamic properties that
allow them to reach the gas-exchanging part of the lung when
inhaled, but are too long to be removed by macro-phages,
the lungs scavengers. Once lodged deep in the lungs they
can inflame the tissue and may eventually lead to scarring
and lung cancer. We have concerns about carbon nanotubes,
which could conceivably cause similar problems to asbestos
if inhaled in quantity as single fibers. Current manufacturing
techniques tend to lead to nanotubes that are clumped into
bundles. However, much current activity is directed toward
developing techniques and coatings to enable the nanotubes to
remain separate. A successful outcome to that research will
lead to many more applications for nanotubes, but will also
mean that they may readily become airborne and inhaled. As
the nanotubes are designed to be insoluble, they may remain
in the lung tissue and induce the free-radical release that
produces inflammation. Until further toxicological studies have
been undertaken, human exposure to airborne nanotubes in
laboratories and workplaces should be minimized [159].
Here public concern has a legitimate basis. We do not,
in fact, understand the interaction of small particles with
cells and tissues, but there are diseases associated with a few
of them: silicosis, asbestosis, black lung [160] [161]. Most
nanomaterials are probably safe: there is no reason to expect
fundamentally new kinds of toxicity from them, and in any
event, they are common in the environment. Moreover, in
commerce, most would be made and used in conditions in
which the nanomaterial was relatively shielded from exposure
to society (an example would be buckytubes compounded into
plastics). Still, we do not know how nanoparticles enter the
body, how they are taken up by the cell, how they are dis-
tributed in the circulation, or how they affect the health of the
organism. If the chemical industry intends to make a serious
entry into nanostructured materials, it would be well advised to
sponsor arms-length, careful, and entirely dispassionate studies
on the effects of existing and new nanoparticles and nanoma-
terials on the behavior of cells and on the health of animals.
This particular aspect of public health will, in any event, be
examined in detail by regulatory agencies concerned with the
effects of nanoparticulate from other sources (especially carbon
nanoparticles in the exhaust from diesel engines) on health.
3) Privacy and Ethical: The most serious risk of nanotech-
nology comes, not from hypothetical revolutionary materials or
systems, but from the uses of evolutionary nanotechnologies
that are already developing rapidly. The continuing extension
of electronics and telecommunications - fast processors, ultra-
dense memory, methods for searching databases, ubiquitous
sensors, electronic commerce and banking, commercial and
governmental record keeping - into most aspects of life is

increasingly making it possible to collect, store, and sort
enormous quantities of data about people [162]. These data
can be used to identify and characterize individuals, and the
ease with which they can be collected and manipulated poses a
direct threat to historical norms of individual privacy. Universal
surveillance - the observation of everyone and everything, in
real time, everywhere; a concept suggested by those most
concerned with terrorism - is not a technology that we would
wish to see cloak a free society, no matter how protectively
intended [163].
The risk of new information technologies emerges naturally
and almost invisibly from an existing technology with which
society is already comfortably familiar, and in which there
is no fundamentally “new” concept, and nothing uniquely
associated with “nano”. There is, however, no question that
information technology has already (and to a far greater
extent that biotechnology) transformed the world. I believe
that it will continue to do so, and that transformation is more
pervasive and deep-seated than anything that will come from
“revolutionary” nanotechnology in the foreseeable future.
In the short term, the societal concerns that arise in the
development of nanotechnologies are centered around ‘who
controls the uses of nanotechnologies’ and ‘who benefits from
uses of nanotechnologies’. Similar concerns apply to any new
technology.
In the longer term, the convergence of nanotechnology with
other technologies is expected to lead to far-reaching develop-
ments, which may raise social and ethical issues. The conver-
gence of nanotechnology with biotechnology, information, and
cognitive sciences may lead to artificial retinas and so help the
blind to see, but more radical forms of human enhancement
have been postulated [164], which, if feasible, would raise
profound ethical issues. A number of the social and ethical
issues that might be generated by nanotechnologies should be
investigated further, so we recommend the establishment of a
multidisciplinary research program to do this. The ethical and
social implications of advanced technologies should form part
of the formal training of all research students and staff working
in these areas.
Public attitudes can play a crucial role in realizing the
potential of technological advances.
B. Prediction
This part predicts the current development trends from the
information and technology aspects considering the state-of-
the-art nanotechnologies.
1) Sustainable Nanomaterials: Nanotechnology is among
the most prominent emerging technologies and it heralded as
a key technology for the 21st century. Potential innovations
offer numerous benefits. There are great expectations among
policymakers, scientists and industry representatives that nan-
otechnology may or will contribute to economic prosperity and
sustainable development (for an up-to-date and comprehensive
overview see Ref. [165]. On the other hand, nanotechnology
has been the subject of an extensive public debate in Europe
and the United States. Obviously, nanotechnology is a case for
technology assessment [166].
The segment of ‘nanotechnology’ that is closest to a
widespread application is the field of ’nanomaterials’. Nano-
materials are an essential part of the overall field of nanotech-
nology. They can be considered as the most important bridge
between basic research and marketable products and processes.
As so-called, ‘enabling technologies’, they are technological
prerequisites for numerous innovations in many technological
fields from comparatively simple technologies for every day
use (like cosmetics or pigments in paints), energy technologies
or information and communication up to biotechnologies –
without their interdependence being always obvious at first
glance. Some nanomaterials – based products and processes
are already in the marketplace, much more will very likely be
seen in the near or mid-term future [166].
Nanomaterials show great economic potential, e.g. by sub-
stituting other materials or by making available new functional-
ities and thus enabling new products and creating new markets.
It is also expected that nanomaterials may contribute to the
reduction of the ecological footprint of classical production
processes by reducing energy and material consumption.
There continues to be a lack of complete understanding
regarding the environmental, health, and safety (EHS) effects
of exposure to engineered nanoscale materials, governments,
industry, and other stakeholders are considering how best to
address EHS issues while continuing to foster the sustainable
commercialization of nanoscale materials. It is generally be-
lieved that sufficient information exists about the toxicity of
some nanoscale materials to suggest a need for caution. The
small size of certain nanoparticles facilitates their uptake into
cells and their movement through the body more readily than
is the case with their conventionally sized counterparts [167].
Other factors contribute to a sense of uncertainty as to
the biological and environmental implications of exposure to
nanoscale materials. Size, shape, surface chemistry, and coat-
ing, for example, can all influence how these materials behave
biologically and in the environment. The fact that nanoscale
materials can have unusual properties, properties that do not
conform to “conventional physics and chemistry, may increase
their commercial value and their potential risks [168].
Nano products are diverse and growing exponentially.
According to the National Nanotechnology Initiative (NNI),
nanoscale materials are used in electronics, pharmaceuti-
cals, chemicals, energy, and biomedical, among other indus-
tries. These products include paints, sporting goods, cosmet-
ics, stain-resistant clothing, electronics, and surface coatings,
among other applications [169].
Sustainable technologies are, in our view, characterized by
high benefits, low risks for the short- and long-term and social
acceptance. It is important to recognize that technologies are
not invented in a vacuum, but emerge from the interplay within
a wide constellation of societal activities and actors [170].
Technologies are therefore, indeed, a product of societal sys-
tems. Sustainability has become an umbrella term for many
different things. While in most approaches environmental
concerns are highlighted, as well economical and social aspects
are stressed. Various definitions of sustainability circulate,
committees struggle about the adequate application of the term
and consultants offer ingenious indicators [171].
Enter green nanotechnology, a conceptual approach to

managing EHS risks potentially posed by nanoscale materials
to ensure their responsible and sustainable development. There
are two key aspects of green nanotechnology. The first involves
nanoproducts that provide solutions to environmental chal-
lenges. These include environmental technologies to remediate
hazardous waste sites and desalinate water, nanotechnology
applications for improving food nutritional value, nanoprod-
ucts that facilitate sensing and monitoring technologies to
detect hazardous pollutants, and other applications. The second
involves producing nanomaterials and nano enabled products
in ways that minimize human and environmental harm. New
nanomaterials can be made using well-established principles of
green chemistry, thus avoiding dependence on processes that
might result in pollutants.
Green engineering principles are applicable as nanomateri-
als increasingly are incorporated into larger, more convention-
ally scaled products. Green engineering embraces the concept
that decisions to protect human health and the environment can
have the greatest impact and cost effectiveness when applied
early to the design and development phase of a process or
product. The most relevant time frame in the green engineer-
ing lifecycle of a nanomaterial is the design stage. Green
engineering considers the full lifecycle of a product, from
the extraction of the materials through manufacturing, product
use, and end of life. Green nanotechnologies which focus on
the full lifecycle can better prepare users for recycling, reuse,
or remanufacture of nanomaterials and nano-enabled products,
thus minimizing generating new hazards through unintended
consequences.
Nanomaterials can be designed to be sustainable. Nanoma-
terials can, for example, be coated so that they do not dissolve
in water or enter biological cells. Some nanomaterials can
be made from renewable ingredients or repurpose nontoxic
biological waste products. Other nanomaterials can be consid-
ered to ensure no part of the product can be the source of
harm to human or environmental health after gainful use and
reclamation opportunities are exhausted.
A subset of greener production includes using nanomateri-
als to “green up” current processes. Catalysts are an important
nanomaterial for this use. As a spherical particle gets smaller
and smaller, it has more surface area proportional to its total
volume. Catalyst reactions take place on the surface, so the
more surface area and less volume the better. Nanomaterials
used as catalysts have high surface areas making them more
efficient and less wasteful, with potentially less polluting
chemical reactions.
Nanoscale membranes are another illustration of green
nano applications. In many chemical reactions, useful products
must be separated from waste. These separations can be
energy intensive, wasteful, or themselves polluting. Nanoscale
membranes can minimize separation steps and energy use.
These examples are merely illustrative of a broad range of
green nanoproducts and processes. While there is reason to
be hopeful, there is also reason to be cautious when creating
and managing these new, unique materials and manufacturing
processes.
2) Nano-Circuits: Nanocircuits are electrical circuits oper-
ating on the nanometer scale, which is well into the quantum
realm, and quantum mechanical effects become very impor-
tant. A variety of proposals have been made to implement
nano-circuits, including Nanowires, single-election transistors,
quantum dot cellular automate, and nanoscale crossbar latches.
Taking the three-dimensional integrated circuit (3D IC) as
an example, 3D IC is an integrated circuit manufactured by
stacking silicon wafers or dies and interconnecting them verti-
cally, e.g., using through-silicon vias (TSVx), so that they be-
have as a single device to achieve performance improvements
at reduced power and smaller footprint than conventional
two dimensional processes. Stacking is important in 3D IC.
There exist many key stacking approaches being implemented
and explored, including die-to-die, die-to-wafer and wafer-to-
wafer. However, these technologies are not mature, and they
carry new challenges, such as cost, yield, design complexity,
TSV-introduced overhead, lack of standards, etc. Thus, these
challenges urgently require new technology to deal with.
Nanotechnology provides a good solution for these challenges.
VI. CONCLUSION
Nanotechnologies offer great opportunities and continue to
attract a lot of attention because of their potential impacts on an
incredibly wide range of industries and markets. Consequently,
this technology is evolving rapidly and will develop faster over
the coming years. The potential new features of nanotech-
nology will be to promote developing the new nanodevices.
Meanwhile, it is also essential to address uncertainties and
the potential problems which nanotechnologies may take in
an economic and safe manner.
REFERENCES
[1] Sargent Jr, John F. ”The National Nanotechnology Initiative: overview,
reauthorization, and appropriations issues.” LIBRARY OF CONGRESS
WASHINGTON DC CONGRESSIONAL RESEARCH SERVICE, De-
cember 2014.
[2] Shapira, Philip, and Jan Youtie. ”Introduction to the symposium issue:
nanotechnology innovation and policycurrent strategies and future trajec-
tories.” The Journal of Technology Transfer 36.6 (2011): 581-586.
[3] ”THE NATIONAL. NANOTECHNOLOGY INITIATIVE. Supplement to
the President’s 2014 Budget”, https://www.whitehouse.gov/sites/default/
files/microsites/ostp/nni fy14 budgetsup.pdf, May 2013
[4] Roco, Mihail C., Chad A. Mirkin, and Mark C. Hersam. Nanotechnology
research directions for societal needs in 2020: retrospective and outlook.
Vol.1.Springer Science & Business Media, 2011.
[5] Ge, Zhi, and Zhili Gao. ”Applications of nanotechnology and nanoma-
terials in construction.” First Inter. Confer. Construc. Develop. Countries
(2008): 235-240.
[6] Bhushan, Bharat. Springer handbook of nanotechnology. Springer Sci-
ence & Business Media, 2010.
[7] Aono, Masakazu, Yoshio Bando, and Katsuhiko Ariga. ”Nanoarchi-
tectonics: Pioneering a new paradigm for nanotechnology in materials
development.” Advanced Materials 24.2 (2012): 150-151.
[8] Whitesides, George M. ”Nanoscience, nanotechnology, and chemistry.”
Small 1.2 (2005): 172-179.
[9] Roco, M. C., R. S. Williams, and P. Alivisatos. ”Nanotechnology Re-
search Directions: IWGN Research Report.” Committee on Technology,
Interagency Working Group on Nanoscience, Engineering and Technol-
ogy (IWGN), National Science and Technology Council (1999).
[10] Mann, S. ”Nanotechnology and Construction. Nanoforum Report
(2006).” (2008).
[11] Whatmore, Roger W., and John Corbett. ”Nanotechnology in the
Marketplace.” Computing and Control Engineering Journal 6.3 (1995):
106-107.

[12] Balaguru, P. N. ”Nanotechnology and concrete: background, opportu-
nities and challenges.” PROCEEDINGS OF THE INTERNATIONAL
CONFERENCE APPLICATION OF TECHNOLOGY IN CONCRETE
DESIGN, 2005.
[13] Murday, James S. ”The coming revolution- Science and technology of
nanoscale structures.” AMPTIAC Newsletter 6.1 (2002): 5-10.
[14] Moriarty, Philip. ”Nanostructured materials.” Reports on Progress in
Physics 64.3 (2001): 297.
[15] Atkinson, William Illsey. Nanocosm: nanotechnology and the big
changes coming from the inconceivably small. AMACOM Div American
Mgmt Assn, 2003.
[16] Kroto, Harold W., et al. ”C 60: buckminsterfullerene.” Nature 318.6042
(1985): 162-163.
[17] Iijima, Sumio. ”Helical microtubules of graphitic carbon.” nature
354.6348 (1991): 56-58.
[18] Peter Unwin, ”Fullerenes(An Overview)”, http://www.ch.ic.ac.uk/local/
projects/unwin/Fullerenes.html
[19] ”Coal Mining and The Most Beautiful Molecule”, https://quantumkool.
wordpress.com/tag/fullerenes/
[20] Bonnell, Dawn A. ”Materials in nanotechnology: New structures, new
properties, new complexity.” Journal of Vacuum Science & Technology
A 21.5 (2003): S194-S206.
[21] Alivisatos, A. Paul, et al. ”Organization of’nanocrystal molecules’ using
DNA.” (1996): 609-611.
[22] Bruchez, Marcel, et al. ”Semiconductor nanocrystals as fluorescent
biological labels.” science 281.5385 (1998): 2013-2016.
[23] Norris, D. J., and M. G. Bawendi. ”Measurement and assignment of
the size-dependent optical spectrum in CdSe quantum dots.” Physical
Review B 53.24 (1996): 16338.
[24] Poole Jr, Charles P., and Frank J. Owens. Introduction to nanotechnol-
ogy. John Wiley & Sons, 2003.
[25] Klabunde, Kenneth J., ed. Nanoscale materials in chemistry. Vol. 1035.
New York: Wiley-Interscience, 2001.
[26] Sobolev, Konstantin, and Miguel Ferrada Gutirrez. ”How nanotechnol-
ogy can change the concrete world.” American Ceramic Society Bulletin
84.10 (2005): 14.
[27] ”Road Science”, http://www.equipmentworld.com/road-science-7/.
[28] Klabunde, Kenneth J., et al. ”Nanocrystals as stoichiometric reagents
with unique surface chemistry.” The Journal of Physical Chemistry
100.30 (1996): 12142-12153.
[29] ”Quantum Mechanics”, http://en.wikipedia.org/wiki/Quantum
mechanics.
[30] ”Nanotechnology”, http://en.wikipedia.org/wiki/Nanotechnology.
[31] Loss, Daniel. ”Quantum phenomena in Nanotechnology.” Nanotechnol-
ogy 20.43 (2009): 430205.
[32] Maksym, P. A., and Tapash Chakraborty. ”Quantum dots in a magnetic
field: Role of electron-electron interactions.” Physical review letters 65.1
(1990): 108.
[33] Ashoori, R. C., et al. ”Single-electron capacitance spectroscopy of
discrete quantum levels.” Physical review letters 68.20 (1992): 3088.
[34] Tarucha, Seigo, et al. ”Shell filling and spin effects in a few electron
quantum dot.” Physical Review Letters 77.17 (1996): 3613.
[35] Bednarek, S., et al. ”Modeling of electronic properties of electrostatic
quantum dots.” Physical Review B 68.15 (2003): 155333.
[36] ”What are the physical and chemical properties of nanoparti-
cles?”,http://ec.europa.eu/health/scientific committees/opinions layman/
en/nanotechnologies/index.htm#3
[37] Gmez-Lpez, Marcos, Jon A. Preece, and J. Fraser Stoddart. ”The art
and science of self-assembling molecular machines.” Nanotechnology 7.3
(1996): 183.
[38] Niemeyer, Christof M. ”Nanoparticles, proteins, and nucleic acids:
biotechnology meets materials science.” Angewandte Chemie Interna-
tional Edition 40.22 (2001): 4128-4158.
[39] http://en.wikipedia.org/wiki/Self-assembly of nanoparticles
[40] Grzelczak, Marek, et al. ”Directed self-assembly of nanoparticles.” ACS
nano 4.7 (2010): 3591-3605.
[41] Bker, Alexander, et al. ”Self-assembly of nanoparticles at interfaces.”
Soft Matter 3.10 (2007): 1231-1248.
[42] http://commons.wikimedia.org/wiki/File:Self-Assembly of
Nanoparticles.jpg
[43] http://en.wikipedia.org/wiki/Magnetic nanoparticles
[44] Tadic, Marin, et al. ”Magnetic properties of novel superparamagnetic
iron oxide nanoclusters and their peculiarity under annealing treatment.”
Applied Surface Science 322 (2014): 255-264.
[45] Lu, AnHui, E. emsp14L Salabas, and Ferdi Schth. ”Magnetic nanopar-
ticles: synthesis, protection, functionalization, and application.” Ange-
wandte Chemie International Edition 46.8 (2007): 1222-1244.
[46] Bitko, D., T. F. Rosenbaum, and G. Aeppli. ”Quantum critical behavior
for a model magnet.” Physical review letters 77.5 (1996): 940.
[47] Carter, S. A., et al. ”New phase boundary in highly correlated, barely
metallic V 2 O 3.” Physical review letters 67.24 (1991): 3440.
[48] Bogenberger, B., and H. V. Lhneysen. ”Tuning of non-Fermi-liquid
behavior with pressure.” Physical review letters 74.6 (1995): 1016.
[49] Maple, M. Brian. ”Interplay between superconductivity and mag-
netism.” Physica B: Condensed Matter 215.1 (1995): 110-126.
[50] Lue, Juh Tzeng, Wen Chu Huang, and Shav Kwen Ma. ”Spin-flip
scattering for the electrical property of metallic-nanoparticle thin films.”
Physical Review B 51.20 (1995): 14570.
[51] Chudnovsky, Eugene M., and Javier Tejada. Macroscopic quantum
tunneling of the magnetic moment. Vol. 4. Cambridge University Press,
2005.
[52] Paulsen, C., et al. ”Macroscopic quantum tunnelling effects of Bloch
walls in small ferromagnetic particles.” EPL (Europhysics Letters) 19.7
(1992): 643.
[53] Zhang, X. X., et al. ”Magnetic properties and domain-wall motion in
single-crystal BaFe 10.2 Sn 0.74 Co 0.66 O 19.” Physical Review B 53.6
(1996): 3336.
[54] Liu, J. H., et al. ”A new method developed in measuring the dielectric
constants of metallic nanoparticles by a microwave double-cavity dielec-
tric resonator.” IEEE microwave and wireless components letters 13.5
(2003): 181-183.
[55] Lue, Juh Tzeng. ”Physical properties of nanomaterials.” Encyclopedia
of Nanoscience and Nanotechnology 10.1 (2007).
[56] Gopalan, E. Veena, et al. ”Evidence for polaron conduction in nanos-
tructured manganese ferrite.” Journal of Physics D: Applied Physics
41.18 (2008): 185005.
[57] Shenoy, S. D., P. A. Joy, and M. R. Anantharaman. ”Effect of me-
chanical milling on the structural, magnetic and dielectric properties of
coprecipitated ultrafine zinc ferrite.” Journal of Magnetism and Magnetic
Materials 269.2 (2004): 217-226.
[58] Ramirez, A. P., et al. ”Giant dielectric constant response in a copper-
titanate.” Solid State Communications 115.5 (2000): 217-220.
[59] Jha, Pika, et al. ”(La 0.4 Ba 0.4 Ca 0.2)(Mn 0.4 Ti 0.6) O 3: A new
titano-manganate with a high dielectric constant and antiferromagnetic
interactions.” Journal of Solid State Chemistry 177.8 (2004): 2881-2888.
[60] Prasad, Bandi Vittal, et al. ”Abnormal high dielectric constant in SmFeO
3 semiconductor ceramics.” Materials Research Bulletin 46.10 (2011):
1670-1673.
[61] Dhaouadi, Hassouna, et al. ”M n 3 O 4 Nanoparticles: Synthesis, Char-
acterization, and Dielectric Properties.” International Scholarly Research
Notices 2012 (2012).
[62] Neamen, Donald A., and Boris Pevzner. Semiconductor physics and
devices: basic principles. Vol. 3. New York: McGraw-Hill, 2003.
[63] Chen, Changxin, and Yafei Zhang. ”Carbon nanotube multi-channeled
field-effect transistors.” Journal of nanoscience and nanotechnology 6.12
(2006): 3789-3793. http://yfzhang.sjtu.edu.cn/en/research.asp?id=7
[64] Bockrath, Marc, et al. ”Chemical doping of individual semiconducting
carbon-nanotube ropes.” Physical Review B 61.16 (2000): R10606.
[65] Derycke, V., et al. ”Carbon nanotube inter-and intramolecular logic
gates.” Nano Letters 1.9 (2001): 453-456.
[66] Reilly, Raymond M. ”Carbon nanotubes: potential benefits and risks of
nanotechnology in nuclear medicine.” Journal of Nuclear Medicine 48.7
(2007): 1039-1042.

[67] Yang, Quan-Hong, et al. ”Adsorption and capillarity of nitrogen in
aggregated multi-walled carbon nanotubes.” Chemical Physics Letters
345.1 (2001): 18-24.
[68] Inoue, S., et al. ”Capillary condensation of N2 on multiwall carbon
nanotubes.” The Journal of Physical Chemistry B 102.24 (1998): 4689-
4692.
[69] Eswaramoorthy, Muthusamy, Rahul Sen, and C. N. R. Rao. ”A study
of micropores in single-walled carbon nanotubes by the adsorption of
gases and vapors.” Chemical physics letters 304.3 (1999): 207-210.
[70] Muris, M., et al. ”Where are the molecules adsorbed on single-walled
nanotubes?.” Surface science 492.1 (2001): 67-74.
[71] Hilding, Jenny, et al. ”Sorption of butane on carbon multiwall nanotubes
at room temperature.” Langmuir 17.24 (2001): 7540-7544.
[72] Korgel, Brian A., and Donald Fitzmaurice. ”Selfassembly of silver
nanocrystals into twodimensional nanowire arrays.” Advanced Materials
10.9 (1998): 661-665.
[73] Morales, Alfredo M., and Charles M. Lieber. ”A laser ablation method
for the synthesis of crystalline semiconductor nanowires.” Science
279.5348 (1998): 208-211.
[74] Costa-Krmer, J. L., N. Garcia, and Hkan Olin. ”Conductance quantiza-
tion in bismuth nanowires at 4 K.” Physical review letters 78.26 (1997):
4990.
[75] Lin, Yu-Ming, Xiangzhong Sun, and M. S. Dresselhaus. ”Theoretical
investigation of thermoelectric transport properties of cylindrical Bi
nanowires.” Physical Review B 62.7 (2000): 4610.
[76] Heremans, Joseph P., et al. ”Thermoelectric power of bismuth nanocom-
posites.” Physical review letters 88.21 (2002): 216801.
[77] Venkatasubramanian, Rama, et al. ”Thin-film thermoelectric devices
with high room-temperature figures of merit.” Nature 413.6856 (2001):
597-602.
[78] Bimberg, Dieter, Marius Grundmann, and Nikolai N. Ledentsov. Quan-
tum dot heterostructures. John Wiley & Sons, 1999.
[79] Bukowski, Tracie J., and Joseph H. Simmons. ”Quantum dot research:
current state and future prospects.” Critical Reviews in Solid State and
Material Sciences 27.3-4 (2002): 119-142.
[80] Beham, E., et al. ”Physics and applications of selfassembled quantum
dots.” physica status solidi (c) 1.8 (2004): 2131-2159.
[81] Queisser, Hans J., and Eugene E. Haller. ”Defects in semiconductors:
some fatal, some vital.” Science 281.5379 (1998): 945-950.
[82] Kelly, Michael J. Low-dimensional semiconductors: materials, physics,
technology, devices. No. 3. Oxford University Press on Demand, 1995.
[83] Poole Jr, Charles P., and Frank J. Owens. Introduction to nanotechnol-
ogy. John Wiley & Sons, 2003.
[84] Sarkar, Kanchan, Nirmal Kr Datta, and Manas Ghosh. ”Interplay
between size and impurity position of doped quantum dot.” Superlattices
and Microstructures 50.1 (2011): 69-79.
[85] Margulis, V. A., and A. V. Shorokhov. ”Hybridimpurity resonances in
anisotropic quantum dots.” Physica E: Low-dimensional Systems and
Nanostructures 41.3 (2009): 483-486.
[86] Mujagic, E., et al. ”Impact of doping on the performance of short-
wavelength InP-based quantum-cascade lasers.” Journal of Applied
Physics 103.3 (2008): 033104-033104.
[87] Bednarek, S., K. Lis, and B. Szafran. ”Quantum dot defined in a
two-dimensional electron gas at a n-Al Ga As Ga As heterojunction:
Simulation of electrostatic potential and charging properties.” Physical
Review B 77.11 (2008): 115320.
[88] Khordad, R. ”Diamagnetic susceptibility of hydrogenic donor impurity
in a V-groove GaAs/Ga 1-x Al x As quantum wire.” The European
Physical Journal B-Condensed Matter and Complex Systems 78.3 (2010):
399-403.
[89] Nistor, S. V., et al. ”Incorporation and localization of substitutional Mn
2+ ions in cubic ZnS quantum dots.” Physical Review B 81.3 (2010):
035336.
[90] Glveren, Berna, et al. ”A parabolic quantum dot with N electrons and
an impurity.” Physica E: Low-dimensional Systems and Nanostructures
30.1 (2005): 143-149.
[91] Wei, Shuyi, Yanping Zhu, and Congxin Xia. ”Donor impurity states in
zinc-blende GaN/AlGaN quantum well: Quantum confinement and laser-
dressed effects.” Superlattices and Microstructures 49.4 (2011): 400-407.
[92] Alivisatos, A. Paul, et al. ”Organization of’nanocrystal molecules’ using
DNA.” (1996): 609-611.
[93] Dantas, Noelio Oliveira, et al. ”Anti-Stokes photoluminescence in
nanocrystal quantum dots.” The Journal of Physical Chemistry B 106.30
(2002): 7453-7457.
[94] Okuno, Tsuyoshi, et al. ”Strong confinement of PbSe and PbS quantum
dots.” Journal of Luminescence 87 (2000): 491-493.
[95] Wilson, Linda. ”International Technology Roadmap for Semiconductors
(ITRS).” Semiconductor Industry Association (2013).
[96] Fahrner, W. R. Nanotechnology and Nanoelectronics. Springer-Verlag
New York Incorporated, 2005.
[97] Taur, Y. ”CMOS scaling into the 21st century: 0.1 m and beyond.”
Microelectronics Reliability 36.4 (1996): 543-543.
[98] https://www.classle.net/book/bipolar-junction-transistor-bjt
[99] http://en.wikipedia.org/wiki/Metalorganic vapour phase epitaxy
[100] Takahashi, Yasuo, et al. ”Silicon single-electron devices and their
applications.” Multiple-Valued Logic, 2000.(ISMVL 2000) Proceedings.
30th IEEE International Symposium on. IEEE, 2000.
[101] Liu, K., et al. ”Simple fabrication scheme for sub-10 nm electrode gaps
using electron-beam lithography.” Applied Physics Letters 80.5 (2002):
865-867.
[102] Takahashi, Yasuo, et al. ”Silicon single-electron devices.” Journal of
Physics: Condensed Matter 14.39 (2002): R995.
[103] Hu, Shu-Fen, et al. ”Proximity effect of electron beam lithography
for single-electron transistor fabrication.” Applied physics letters 85.17
(2004): 3893-3895.
[104] Bachtold, A., et al. ”Scanned probe microscopy of electronic transport
in carbon nanotubes.” Physical review letters 84.26 (2000): 6082.
[105] McEuen, Paul L., Michael S. Fuhrer, and Hongkun Park. ”Single-
walled carbon nanotube electronics.” IEEE transactions on nanotechnol-
ogy 1.1 (2002): 78-85.
[106] Kong, Jing, et al. ”Synthesis of individual single-walled carbon nan-
otubes on patterned silicon wafers.” Nature 395.6705 (1998): 878-881.
[107] Tans, Sander J., Alwin RM Verschueren, and Cees Dekker. ”Room-
temperature transistor based on a single carbon nanotube.” Nature
393.6680 (1998): 49-52.
[108] Guillorn, M. A., et al. ”Operation of individual integrally gated carbon
nanotube field emitter cells.” Applied physics letters 81.15 (2002): 2860-
2862.
[109] Martel, R. al, et al. ”Single-and multi-wall carbon nanotube field-effect
transistors.” Applied Physics Letters 73.17 (1998): 2447-2449.
[110] Kong, Jing, et al. ”Chemical profiling of single nanotubes: Intramolec-
ular pnp junctions and on-tube single-electron transistors.” Applied
Physics Letters 80.1 (2002): 73-75.
[111] Li, J., et al. ”Highly-ordered carbon nanotube arrays for electronics
applications.” Applied physics letters 75.3 (1999): 367-369.
[112] Hu, Jiangtao, et al. ”Controlled growth and electrical properties of
heterojunctions of carbon nanotubes and silicon nanowires.” Nature
399.6731 (1999): 48-51.
[113] Park, W. I., et al. ”Schottky nanocontacts on ZnO nanorod arrays.”
Applied Physics Letters 82.24 (2003): 4358-4360.
[114] Chua, Leon O. ”Memristor-the missing circuit element.” Circuit The-
ory, IEEE Transactions on 18.5 (1971): 507-519.
[115] Shahar Kvatinsky, ”Memristor-Based Circuits and Architectures”, PhD
thesis, May 2014.
[116] Rozenberg, M. J., I. H. Inoue, and M. J. Sanchez. ”Nonvolatile memory
with multilevel switching: a basic model.” Physical review letters 92.17
(2004): 178302.
[117] Borghetti, Julien, et al. ”Memristiveswitches enable statefullogic op-
erations via material implication.” Nature 464.7290 (2010): 873-876.
[118] Jo, Sung Hyun, et al. ”Nanoscale memristor device as synapse in
neuromorphic systems.” Nano letters 10.4 (2010): 1297-1301.
[119] Linares-Barranco, Bernab, and Teresa Serrano-Gotarredona. ”Memris-
tance can explain spike-time-dependent-plasticity in neural synapses.”
Nature precedings 1 (2009): 2009.

[120] Kvatinsky, Shahar, et al. ”Models of memristors for SPICE simula-
tions.” Electrical & Electronics Engineers in Israel (IEEEI), 2012 IEEE
27th Convention of. IEEE, 2012.
[121] Prodromakis, Themistoklis, and Chris Toumazou. ”A review on mem-
ristive devices and applications.” Electronics, Circuits, and Systems
(ICECS), 2010 17th IEEE International Conference on. IEEE, 2010.
[122] Raoux, Simone, et al. ”Phase change materials and phase change
memory.” MRS Bulletin 39.08 (2014): 703-710.
[123] Wang, W. J., et al. ”Fast phase transitions induced by picosecond
electrical pulses on phase change memory cells.” Applied Physics Letters
93.4 (2008): 043121.
[124] Loke, D., et al. ”Breaking the speed limits of phase-change memory.”
Science 336.6088 (2012): 1566-1569.
[125] Bruns, G., et al. ”Nanosecond switching in GeTe phase change
memory cells.” Applied physics letters 95.4 (2009): 043108.
[126] Nirschl, T., et al. ”Write strategies for 2 and 4-bit multi-level phase-
change memory.” Electron Devices Meeting, 2007. IEDM 2007. IEEE
International. IEEE, 2007.
[127] Kim, Cheolkyu, et al. ”Fullerene thermal insulation for phase change
memory.” Applied Physics Letters 92.1 (2008): 013109.
[128] Jackson, Bryan L., et al. ”Nanoscale electronic synapses using phase
change devices.” ACM Journal on Emerging Technologies in Computing
Systems (JETC) 9.2 (2013): 12.
[129] Suri, Manan, et al. ”Phase change memory as synapse for ultra-dense
neuromorphic systems: Application to complex visual pattern extraction.”
Electron Devices Meeting (IEDM), 2011 IEEE International. IEEE, 2011.
[130] Kuzum, Duygu, et al. ”Nanoelectronic programmable synapses based
on phase change materials for brain-inspired computing.” Nano letters
12.5 (2011): 2179-2186.
[131] Suri, Manan, et al. ”Physical aspects of low power synapses based
on phase change memory devices.” Journal of Applied Physics 112.5
(2012): 054904.
[132] Yonzon, Chanda Ranjit, et al. ”Towards advanced chemical and
biological nanosensorsan overview.” Talanta 67.3 (2005): 438-448.
[133] Riu, Jordi, Alicia Maroto, and F. Xavier Rius. ”Nanosensors in
environmental analysis.” Talanta 69.2 (2006): 288-301.
[134] Hierold, Christofer, et al. ”Nano electromechanical sensors based on
carbon nanotubes.” Sensors and Actuators A: Physical 136.1 (2007): 51-
61.
[135] Li, Chunyu, Erik T. Thostenson, and Tsu-Wei Chou. ”Sensors and
actuators based on carbon nanotubes and their composites: a review.”
Composites Science and Technology 68.6 (2008): 1227-1249.
[136] Akyildiz, Ian F., and Josep Miquel Jornet. ”Electromagnetic wireless
nanosensor networks.” Nano Communication Networks 1.1 (2010): 3-19.
[137] Lima, Teik-Cheng, and Seeram Ramakrishnaa. ”A conceptual review
of nanosensors.” (2006).
[138] ”GRANET: Graphene-enabled Nanonetworks in the Terahertz
Band”, http://www.ece.gatech.edu/research/labs/bwn/projects/granet/
projectdescription.html
[139] Lee, Junsok, and Soohyun Kim. ”Manufacture of a nanotweezer using
a length controlled CNT arm.” Sensors and Actuators A: Physical 120.1
(2005): 193-198.
[140] Falconi, Christian, Arnaldo DAmico, and Zhong Lin Wang. ”Wireless
joule nanoheaters.” Sensors and Actuators B: Chemical 127.1 (2007):
54-62.
[141] Jordan, A., et al. ”Cellular uptake of magnetic fluid particles and their
effects on human adenocarcinoma cells exposed to AC magnetic fields
in vitro.” International journal of hyperthermia 12.6 (1996): 705-722.
[142] Wang, Zhong Lin. ”Towards SelfPowered Nanosystems: From Nano-
generators to Nanopiezotronics.” Advanced Functional Materials 18.22
(2008): 3553-3567.
[143] Yang, Rusen, et al. ”Converting biomechanical energy into electricity
by a muscle-movement-driven nanogenerator.” Nano Letters 9.3 (2009):
1201-1205.
[144] Ponomarenko, L. A., et al. ”Chaotic Dirac billiard in graphene quan-
tum dots.” Science 320.5874 (2008): 356-358.
[145] Tan, Kuan Yen, et al. ”Transport spectroscopy of single phosphorus
donors in a silicon nanoscale transistor.” Nano letters 10.1 (2009): 11-15.
[146] Bennewitz, Roland, et al. ”Atomic scale memory at a silicon surface.”
Nanotechnology 13.4 (2002): 499.
[147] Parkin, Stuart SP, Masamitsu Hayashi, and Luc Thomas. ”Magnetic
domain-wall racetrack memory.” Science 320.5873 (2008): 190-194.
[148] Datta, Supriyo. Electronic transport in mesoscopic systems. Cambridge
university press, 1997.
[149] Lin, Y-M., et al. ”100-GHz transistors from wafer-scale epitaxial
graphene.” Science 327.5966 (2010): 662-662.
[150] Moon, J. S., et al. ”Epitaxial-graphene RF field-effect transistors on
Si-face 6H-SiC substrates.” Electron Device Letters, IEEE 30.6 (2009):
650-652.
[151] Joy, Bill. ”Why the future doesnt need us.” Nanoethicsthe ethical and
social implicatons of nanotechnology (2000): 17-39.
[152] Phoenix, Chris, and Eric Drexler. ”Safe exponential manufacturing.”
Nanotechnology 15.8 (2004): 869.
[153] Stephenson, Neal. ”The Diamond Age or, A Young Ladys Illustrated
Primer. 1995.” New York: Bantam (2000).
[154] Bykov, V. A., A. V. Emelyanov, and E. A. Poltoratski. ”Nanotechnol-
ogy methods and creation of the terabit storage.” NANOSTRUCTURES
(1999): 460.
[155] Brumfiel, Geoff. ”Nanotechnology: A little knowledge...” Nature
424.6946 (2003): 246-248.
[156] Ferin, Juraj, et al. ”Increased pulmonary toxicity of ultrafine particles?
I. Particle clearance, translocation, morphology.” Journal of Aerosol
Science 21.3 (1990): 381-384.
[157] Oberdrster, Gnter. ”Pulmonary effects of inhaled ultrafine particles.”
International archives of occupational and environmental health 74.1
(2000): 1-8.
[158] Mossman, Brooke T., et al. ”Asbestos: scientific developments and
implications for public policy.” Science 247.4940 (1990): 294-301.
[159] Dowling, Ann P. ”Development of nanotechnologies.” Materials Today
7.12 (2004): 30-35.
[160] Warheit, David B. ”Nanoparticles: health impacts?.” Materials today
7.2 (2004): 32-35.
[161] Borm, Paul JA, and Wolfgang Kreyling. ”Toxicological hazards of
inhaled nanoparticlespotential implications for drug delivery.” Journal of
nanoscience and nanotechnology 4.5 (2004): 521-531.
[162] Anton, Philip S., Richard Silberglitt, and James Schneider. The global
technology revolution: bio/nano/materials trends and their synergies with
information technology by 2015. Rand Corporation, 2001.
[163] Anderson, James G., and Kenneth W. Goodman, eds. Ethics and
information technology: a case-based approach to a health care system
in transition. Springer Science & Business Media, 2002.
[164] Bainbridge, William Sims, and Mihail C. Roco. ”Converging Tech-
nologies for Improving Human Performance..” (2003).
[165] Paschen, Herbert, et al. Nanotechnologie: Forschung, Entwicklung,
Anwendung. Springer-Verlag, 2006.
[166] Fleischer, Torsten, Michael Decker, and Ulrich Fiedeler. ”Assess-
ing emerging technologiesMethodological challenges and the case of
nanotechnologies.” Technological Forecasting and Social Change 72.9
(2005): 1112-1121.
[167] Oberdrster, Gnter, Eva Oberdrster, and Jan Oberdrster. ”Nanotoxicol-
ogy: an emerging discipline evolving from studies of ultrafine particles.”
Environmental health perspectives (2005): 823-839.
[168] Bergeson, Lynn L. ”Sustainable nanomaterials: emerging governance
systems.” ACS Sustainable Chemistry & Engineering 1.7 (2013): 724-
730.
[169] Woodrow Wilson International Center for Scholars. ”A nanotechnol-
ogy consumer products inventory.” (2007).
[170] Crow, Michael M., and Daniel Sarewitz. ”Nanotechnology and societal
transformation.” Societal implications of nanoscience and nanotechnol-
ogy (2001): 45.
[171] Helland, Aasgeir, and Hans Kastenholz. ”Development of nanotech-
nology in light of sustainability.” Journal of Cleaner Production 16.8
(2008): 885-888.