G. E. Cirlin

Saint Petersburg Academic University · Epitaxial nanotechnologies

An approach to the fabrication of LED structure based on GaN nanowires with thick core-shell InGaN insertions with high indium content is studied. The results of optical measurements demonstrate the photoluminescence from the InGaN insertions in the green spectrum at room temperature. The study of electrical properties shows typical diode dependenc...

We present a study with a numerical model based on k→·p→, including electromechanical fields, to evaluate the electromechanical and optoelectronic properties of single GaAs quantum dots embedded in direct band gap AlGaAs nanowires. The geometry and the dimensions of the quantum dots, in particular the thickness, are obtained from experimental data...

Hybrid nanostructures based on InGaN nanowires with decorated plasmonic silver nanoparticles are investigated in the present study. It is shown that plasmonic nanoparticles induce the redistribution of room temperature photoluminescence between short-wavelength and long-wavelength peaks of InGaN nanowires. It is defined that short-wavelength maxima...

Wurtzite AlGaAs is a technologically promising yet unexplored material. Here we study it both experimentally and numerically. We develop a complete numerical model based on an 8-band k→·p→ method, including electromechanical fields, and calculate the optoelectronic properties of wurtzite AlGaAs nanowires with different Al content. We then compare t...

Semiconductor nanowires are the perfect platform for nanophotonic applications owing to their resonant, waveguiding optical properties and technological capabilities providing control over their crystalline and chemical compositions. The vapor-liquid-solid growth mechanism allows the formation of hybrid metal-dielectric nanostructures promoting sub...

The effect of cooling conditions in the plasma-assisted molecular-beam epitaxy growth on the structural and optical properties of InGaN nanostructures is studied. It is shown that cooling of the samples without nitrogen plasma contributes to the suppression of phase separation in InGaN nanostructures. The integrated intensity of photoluminescence f...

The paper presents an approach to growth of GaN nanowires with thick core-shell InGaN insertions with a high indium content for creation of LED structure. The study of the electrical properties shows typical diode dependence. The results obtained can make a significant contribution to the development of light emitting diodes on silicon substrates.

GaN nanowires were grown using selective area plasma-assisted molecular beam epitaxy on SiOx/Si(111) substrates patterned with microsphere lithography. For the first time, the temperature–Ga/N2 flux ratio map was established for selective area epitaxy of GaN nanowires. It is shown that the growth selectivity for GaN nanowires without any parasitic...

The direct integration of epitaxial III-V and III-N heterostructures on Si substrates is a promising platform for the development of optoelectronic devices. Nanowires, due to their unique geometry, allow for the direct synthesis of semiconductor light-emitting diodes (LED) on crystalline lattice-mismatched Si wafers. Here, we present molecular beam...

We investigate the photoluminescence of a film obtained by the uniform deposition of a colloidal solution of CdSe/ZnS quantum dots capped by trioctylphosphine oxide on an array of isolated InP/InAsP/InP nanowires and subsequently removed from the substrate. The photoluminescence spectrum of the film shows emission bands corresponding to InAsP nano-...

Combinations of III–V nanowires with quantum dots are promising building blocks for quantum light sources. In this work we show, for the first time, the results of growing AlGaAs nanowires with InGaAs quantum dots by molecular‐beam epitaxy on a silicon substrate. The optimal growth temperature was determined and the physical properties of the grown...

Tailorable synthesis of axially heterostructured epitaxial nanowires (NWs) with a proper choice of materials allows for the fabrication of novel photonic devices, such as a nanoemitter in the resonant cavity. An example of the structure is a GaP nanowire with ternary GaPAs insertions in the form of nano-sized discs studied in this work. With the us...

A model of spontaneous formation of the core-shell structure in (In,Ga)As nanowire grown via molecular beam epitaxy without independent radial growth is proposed. Within the framework of the proposed model, the distribution of In across the axis of the nanowire was fitted. Keywords: core-shell nanowire, ternary nanowire, InGaAs nanowire, radial nan...

The results of experimental studies on the synthesis by molecular-beam epitaxy of AlGaAs nanowires with InGaAs quantum dots are presented. It was shown that, as in the case of the InP/InAsP material system, the formation of predominantly two objects is observed in the body of AlGaAs nanowire: InGaAs quantum dot due to axial growth and InGaAs quantu...

In this work, InGaN nanowires with a high In content were grown, for the first time on hybrid SiC/Si substrates and compared with InGaN nanowires grown on Si. It was shown that InGaN nanowires on SiC/Si have lower indium content (by about 10%) compared to the nanowires on Si. The results can be beneficial for studying the growth mechanisms of InGaN...

The possibility of obtaining spectra of the complex refractive index of mononucleotide films deposited on a polished silicon wafer in the terahertz (THz) range has been shown for the first time. The transmission of biopolymer samples with a THz spectrometer was measured. The natural absorption frequencies and refractive index spectrum of adenosine...

Ammonia is an inorganic agent found both in nature and in the human body, which is of great interest for modern sensory applications. Here we use GaP, GaN and GaAs epitaxial nanowires as sensitive elements of the ammonia sensors fabricated via a simple protocol on the platform with golden interdigital contacts. Impedancemetry is used to study chang...

The influence of the growth time on the structural properties of InGaN nanowires grown on Si substrate by plasma-assisted molecular beam epitaxy are studied. Under appropriate other growth conditions, the growth for 2h leads to the formation of separated nanowires, whereas the growth for 2h 30min and 3h leads to the formation of nanostructures such...

In modern optoelectronics, arrays or single nanowires (NWs) of III-N materials, in particular InGaN, separated from the original substrates are used to fabricate light-emitting diodes or single photon sources. This work describes a technology of separation super-dense arrays or arrays of partially-coalesced InGaN nanowires and single nanowires from...

Heterostructured AlGaAs/Ge/AlGaAs core-multishell nanowires having hexagonal crystal structure were synthesized by molecular beam epitaxy. Formation of 2-3 nm Ge quantum well structure was demonstrated. Raman characterization revealed a 200 cm ⁻¹ peak corresponded to hexagonal phases of germanium.

The development of a new semiconductor element base is necessary to create a new generation of applications. At present time, the synthesis of high-quality hybrid nanostructures based on III-V quantum dots in the body of nanowires of a wide range of material systems is an urgent and important task. In work hybrid III-V nanostructures based on QDs i...

The effect of the crystal lattice mismatch between single p-GaAs nanowire grown on p-Si substrate on the solar cell efficiency is studied. The study is performed by measuring the I-V curves under red (wavelength=650 nm) laser illumination. The measurement of the single nanowire was done by conductive atomic force microscopy (C-AFM). The measured cu...

We demonstrate growth of AlGaAs NWs with GaAs QDs and InP NWs with InAsP QDs on silicon substrates. Results of GaAs QDs optical properties study have shown that these objects are sources of single photons. In case of InP NWs with InAsP QDs, the results showed that ~ 100% of homogeneously oriented NWs were formed with good optical quality of this sy...

The possibility of AlGaAs nanowires with GaAs quantum dots and InP nanowires with InAsP quantum dots growth by molecular-beam epitaxy on silicon substrates has been demonstrated. Results of GaAs quantum dots optical properties studies have shown that these objects are sources of single photons. In case of InP nanowires with InAsP quantum dots, the...

The possibility of the controlled removal of GaN nanowires (NWs) from an SiO x inhibitor layer of patterned SiO x /Si substrates has been demonstrated. It has been found that the wet KOH etching preserves the selectively grown GaN NWs on Si surface, whereas the GaN NWs grown on inhibitor SiOx layer are removing. The effect is described by the diffe...

Control of directionality of emissions is an important task for the realization of novel nanophotonic devices based on nanowires. Most of the existing approaches providing high directionality of the light emitted from nanowires are based on the utilization of the tapered shape of nanowires, serving as nanoantenna coupling with the light waveguided...

We demonstrate flexible red light-emitting diodes based on axial GaPAs/GaP heterostructured nanowires embedded in polydimethylsiloxane membranes with transparent electrodes involving single-walled carbon nanotubes. The GaPAs/GaP axial nanowire arrays were grown by molecular beam epitaxy, encapsulated into a polydimethylsiloxane film, and then relea...

We present experimental data on the rapid (∽ 4.4 nm/s) axial growth rate of narrow (∽ 9 nm in radius) InAs nanowires obtained by Au-catalyzed molecular beam epitaxy on Si substrates at a low surface temperature of 270 oC.These nanowires exhibit pure wurtzite crystal structure and an unusually high ratio of the average nanowire length over the effec...

Tailorable synthesis of III-V semiconductor heterostructures in nanowires (NWs) enables new approaches with respect to designing photonic and electronic devices at the nanoscale. We present a comprehensive study of highly controllable self-catalyzed growth of gallium phosphide (GaP) NWs on template-free silicon (111) substrates by molecular beam ep...

Young's modulus of tapered mixed composition (zinc-blende with a high density of twins and wurtzite with a high density of stacking faults) Gallium Phosphide (GaP) nanowires (NWs) was investigated by atomic force microscopy (AFM). Experimental measurements were performed by obtaining bending profiles of as-grown inclined GaP NWs deformed by applyin...

InGaN nanostructures are among the most promising candidates for visible solid-state lighting and renewable energy sources. To date, there is still a lack of information about the influence of the growth conditions on the physical properties of these nanostructures. Here, we extend the study of InGaN nanowires growth directly on Si substrates by pl...

In this work we investigate effects of the crystal phase, twinning defects and shell formation on the work function distribution over the surface of axially heterostructured GaP/GaPAs/GaP nanowires via frequency-modulated Kelvin probe force microscopy. Analysis of experimental data is supported by theoretical model based on density functional theor...

The passivation influence by ligands coverage with trioctylphosphine oxide (TOPO) and TOPO including colloidal CdSe/ZnS quantum dots (QDs) on optical properties of the semiconductor heterostructure, namely an array of InP nanowires (NWs) with InAsP nanoinsertion grown by Au-assisted molecular beam epitaxy on Si (111) substrates, was investigated. A...

III-V nanowires (NWs) are a promising technology for piezotronic and nanooptoelctronic applications. In this work, we investigate the processes of fabricating a structure with InP NW arrays on a silicon substrate for piezotronic applications. The coating of the NW array with a polymer and the fabrication of a transparent electrical contact to NWs i...

We present the results of selective-area growth of GaN nanowires by molecular beam epitaxy on patterned SiO x /Si substrates without using seed layers. The morphological and optical properties of selectively grown GaN nanowires are compared to the properties of GaN nanowires grown on the amorphous SiO x layer. The experimental results show that the...

GaAs quantum dots in nanowires are one of the most promising candidates for scalable quantum photonics. They have excellent optical properties, can be frequency-tuned to atomic transitions, and offer a robust platform for fabrication of multi-qubit devices that promise to unlock the full technological potential of quantum dots. Coherent resonant ex...

In this work, it is experimentally shown that the etching of GaN or InGaN NWs in the KOH solution allows managing the morphology and optical properties of the nanowires array. Thinning rate of GaN nanowires is 5 times slower than the rate for InGaN nanowires along semi-polar and non-polar direction for nanowires with Ga-polar crystal structure. The...

This work proposes new chemical and mechanical materials and techniques for III-V semiconductor NW/silicone membrane formation and optoelectronic device fabrication. Molecular beam epitaxy (MBE)-synthesized n-, p- and i-GaP NWs were encapsulated by introduced G-coating method into synthesized polydimethylsiloxane- graft -polystyrene and released fr...

A possibility of the AlGaAs nanowires with multiply GaAs QDs MBE growth on silicon substrates has been demonstrated. The morphological on optical properties of grown structures were studied.

The work is devoted to the study of electrical properties of InGaN nanostructures with branched morphology (NSs) on p-type Si substrates. It was found that the IV curves between InGaN NSs and p-Si are close to linear, which could indicate a tunneling conductivity. Such unique structures as InGaN NSs on p-Si can be used as building blocks for water...

In this paper, we demonstrate and investigate the process of wet chemical etching in KOH solutions of InGaN quantum dots/GaN nanorods with the average height of heterostructure 330 nm and lateral size up to 120 nm. Morphological studying showed a significant thinning of nanorods to 40-80 nm and the shape transformation from trapezoidal to cylindric...

Controlled growth of heterostructured nanowires and mechanisms of their formation have been actively studied during the last decades due to perspectives of their implementation. Here, we report on the self-catalyzed growth of axially heterostructured GaPN/GaP nanowires on Si(111) by plasma-assisted molecular beam epitaxy. Nanowire composition and s...

Flexible optoelectronic structures are required in a wide range of applications. Large scale modified silicone-embedded n-GaP nanowire arrays of a record 6 µm thin membranes were studied. A homogeneous silicone encapsulation was enabled by G-coating using a heavy-load centrifuge. The synthesized graft-copolymers of polydimethylsiloxane (PDMS) and p...

The reduction of substrate temperature is important in view of the integration of III–V materials with a Si platform. Here, we show the way to significantly decrease substrate temperature by introducing a procedure to create nanoscale holes in the native-SiOx layer on Si(111) substrate via In-induced drilling. Using the fabricated template, we succ...

The ability to engineer nonlinear optical emission from nanostructures is a key challenge to create efficient and compact components for integrated devices. This paper shows a method to control and manipulate the directionality of second‐harmonic generation emission by engineering geometry and position of rod nanoantennas. Single and dimer nanoante...

Research regarding ways to increase solar cell efficiency is in high demand. Mechanical deformation of a nanowire (NW) solar cell can improve its efficiency. Here, the effect of uniaxial compression on GaAs nanowire solar cells was studied via conductive atomic force microscopy (C-AFM) supported by numerical simulation. C-AFM I–V curves were measur...

Strain engineering is a powerful tool that allows tuning of the optical and electronic properties of the nanostructures opening new pathways for the nanowire (NW)-based practical applications. We introduce a complex study of individual bent GaP NWs based on micro-Raman mapping. Numerical modeling of the mapping data is performed to analyze spatial...

We report a novel mechanism that allows the incorporation of Si into GaN nanowires up to and beyond the solubility limit. It appears during growth on vicinal (misoriented) SiC/Si hybrid substrates at step bunches. Nanowires that are grown at these locations become heavily Si doped. Such high Si concentrations were verified by secondary secondary-io...

A possibility of GaN NWs and InGaN nanostructures of a branched morphology MBE growth on SiC/Si and Si substrate has been demonstrated. It was found that the intensity of the photoluminescence spectrum of the GaN NWs on SiC/Si(111) substrate integrally more than 2 times higher than that of the best structures of GaN NWs without a buffer layer of si...

The effect of hydrogen plasma treatment on the electrical and optical properties of GaN NWs/Si based vertical hetero structures synthesized by the method of plasma molecular beam epitaxy is studied. The effect of treatment has been carefully studied by variation of the passivation duration. Measurements of the electron beam-induced current (EBIC) t...

In the article, we demonstrate the growth of AlGaAs nanowires on silicon substrates. It is shown that a controlled growth of short GaAs insertions inside AlGaAs nanowires is possible. Optically, such segments shows sharp and intense quantum dot - like emission lines. Our work opens new prospects for integration of direct bandgap semiconductors and...

The luminescence photodynamics of an array of InP/InAsP/InP nanowires formed via molecular beam epitaxy onto a Si(III) substrate is investigated in this work. Using several kinetic models, the experimental data acquired by a 633-nm room-temperature laser excitation have been analyzed. The kinetics of luminescence decay of the InAsP nanoinsert is sh...

The influence of hydrogen plasma treatment on electrical and optical properties of the vertical GaN nanowires (NWs)/Si heterostructures synthesized via plasma assisted molecular beam epitaxy is studied. The effect of the treatment is thoroughly studied via variation of the passivation duration. Photoluminescence (PL) investigation demonstrates that...

In the article, the study of the morphology, crystal structure and chemical composition of In x Ga 1-x N nanostructures is presented. Scanning electron microscopy measurements show that the sample has a structure consisting of nanotubes, on top of which an array of nanocrystals (so-called “nanoflowers”) is formed. The results of transmission electr...

Rubber materials are the key components of flexible optoelectronic devices, especially for the light-emitting diodes based on arrays of inorganic nanowires (NWs). This paper reports on polydimethylsiloxane-graft-polystyrene as new flexible substrate of GaP NW array structures. The NWs were encapsulated by the firstly introduced G-coating method to...

Semiconducting nanowires, unlike bulk, can be grown in both wurtzite and zincblende crystal phases. This unique feature allows for growth and investigation of technologically important and previously unexplored materials, such as wurtzite AlGaAs. Here we grow a series of wurtzite AlGaAs nanowires with Al content varying from 0.1 to 0.6, on silicon...

We show two functionalities of GaAs nanowires to control the second harmonic generation: beam steering up to 30° in sliced nanoantenna and three orders of magnitude enhancement within 3% stretching in mechanically tunable metamaterials.

A possibility of InGaN nanostructures of a branched morphology MBE growth on Si substrate has been demonstrated. The results of morphological studies have shown that InGaN synthesis occurs in several stages. InGaN nanostructures turned out to be optically active at room temperature and have a wide radiation visible range.

Investigation of ZnO thin films synthesis using RF magnetron sputtering deposition in the Ar/O 2 plasma gas mixture at different O 2 composition and at different growth temperatures is presented. The effect growth process on structural (morphology and orientation films, grain sizes, lattice parameters) and optical (transmittance, absorption, refrac...

In this work, we present the results of photoluminescence measurements of wurtzite AlGaAs nanowires, coupled with the transmission electron microscopy structural analysis. AlGaAs NWs were grown by molecular beam epitaxy under the nominal aluminum content of 0.3 - 0.8. The results of TEM measurements demonstrated wurtzite crystal structure of AlGaAs...

The experimental and modelling results of the investigation of photovoltaic properties of the InP nanowires grown on p-Si substrate are presented. It is shown that InP 2D-layer between nanowires on Si is II-type heterojanction. The resulting structure exhibits an open-circuit voltage (Voc) of 0,37 V, a short-circuit current density (Jsc) of 10.6 mA...

Energy harvesting is an area that presents the greatest potential for powering wireless low-energy electronics. Development of semiconductor-based energy harvesting is of interest. Herein we focus on studying two different energy harvesting mechanisms in indium phosphide. Piezoelectric harvesting was checked by bending vertical InP nanowires with c...

This work proposes new chemical and mechanical materials and techniques for III-V semiconductor NW/silicone membrane formation and optoelectronic device fabrication. Molecular beam epitaxy (MBE)-synthesized n-, p- and i-GaP NWs were encapsulated by introduced G-coating method into synthesized polydimethylsiloxane-graft-polystyrene and released from...

A composite nanostructure based on quasi-one-dimensional InP nanowires with an InAsP nanoinsert, grown on a Si(111) substrate by the method of molecular-beam epitaxy, and CdSe/ZnS zero-dimensional colloidal quantum dots is reported for the first time. The nonradiative resonance energy transfer between components of the hybrid nanostructure, namely,...

We study growth and properties of the self‐catalyzed heterostructured GaP nanowires (NWs) with GaP1‐x As x insertions in the form of nanodiscs (NDs) grown by means of molecular beam epitaxy on Si (111) substrate. To obtain the NDs with the different composition and optoelectronic properties the ratio of As and P fluxes is varied. Structural propert...

Long-term stability is an issue for semiconductor gas sensors, because the sensing material normally needs to be exposed to ambient air (oxygen and water molecules). InAs nanowires (NWs) feature good gas sensing properties at room temperature, but the NWs can be oxidized in air. In this paper, the gas sensing properties of InAs/InP core/shell NWs w...

We have studied the role of EL2 centers in formation of the photoelectric response of an array of radial n-type GaAs/AlxGa1 –xAs (x = 0.3) nanowires (NWs) grown by molecular beam epitaxy on a p-type silicon substrate. Results revealed a significant decrease in the time of NW photoresponse recovery as compared to that in a bulk crystal upon the tran...

The role of Si (111) substrate surface preparation and buffer layer composition in the growth, electronic and optical properties of the GaN nanowires (NWs) synthesized via plasma-assisted molecular beam epitaxy is studied. A comparison study of GaN NWs growth on the bare Si (111) substrate, silicon nitride interlayer, predeposited AlN and GaOx buff...

We propose a new insight into the mechanism of low-temperature Au-assisted growth of InAs nanowires during molecular beam epitaxy (MBE). The nanowire MBE growth was achieved at the temperature of 270 ℃ on both Si(111) and SiC/Si(111) substrates. A special procedure of substrate preparation was used to obtain a high yield of nanowires grown perpendi...