Jingwei Guo

Yan Shan University | YSU · School of Information Science and Engineering

In this paper, GaAs nanowires with different V/III ratios (70, 140, 280 and 560) were vertically grown from bottom to top on GaAs substrates by using metal organic chemical vapor deposition based on gold assisted vapor-liquid-solid mechanism. It is found that the growth rate of nanowires is inversely proportional to their V/III ratio. And the V/III...

Vertical GaAs nanowires were grown on different doped substrates via Metal Organic Chemical Vapor Deposition by catalyst assisted vapor-liquid-solid mechanism. It is found that both n and p type doped substrates affect catalyst distribution during the formation of alloy catalysts. The catalyst density decreases with an increase in the doping concen...

The light trapping performance of Si nanowire with different inclination angles were systematically studied by COMSOL Multiphysics. The inclined nanowires with inclination angles smaller than 60° show greater light trapping ability than their counterparts of the vertical nanowires. The Si solar cell with the inclined nanowires of the optimal parame...

Multi-walled carbon nanotube arrays could be easily grown on the central position in the quartz tube. SEM images show the well-aligned carbon nanotube feature. They clearly exhibit the highly ordered array structures and a very good alignment of carbon nanotube arrays with high packing densities.

Multi-walled carbon nanotube arrays (MWCNTAs) were grown by thermal chemical vapor deposition (TCVD) in a horizontal furnace reactor. The scanning electron microscopy (SEM) results show that MWCNTAs grown on the bottom and the central of the quartz tube are different in one experiment. Moreover, the MWCNTAs grown on the central position are more al...

A new crystalline silicon solar cell with Si nanocone arrays on the top and Al nanohemisphere arrays on bottom surface were proposed. The light-trapping ability were systematically studied by COMSOL Multiphysics. The nanocone arrays benefit light-trapping by introducing gradient change of refractive index and coupling the incoming light into optica...

To improve the efficiency and reduce the cost of solar cells, it's important to enhance the light absorption. Within the visible solar spectrum based on optimization simulations by COMSOL Multiphysics, the optical absorption of silicon cylindrical nanowires, nanocones and inverted nanocones was calculated respectively. The results reveal that the a...

In this letter, the top-down and bottom-up segmentations were integrated together to realize high-performance organic devices and circuits. By combining photolithography with in situ polymerization, high conductive polypyrrole was patterned and used as electrodes for organic field-effect transistors (OFETs). With pentacene as P-type organic semicon...

Diodes as basic structures for semiconductor devices can be realized using a heterojunction or p-type/n-type doping. As for doping, the introduced impurities could substantially reduce the carrier mobility. For heterojunctions, on the other hand, engineering of the bandgap is required via integrating different materials, which is normally limited b...

Bandgap engineering is important for realizing high-performance semiconductor devices. In this paper, an investigation on the nanowire diode with a tapered InAs/InP core–shell structure was carried out. The strain distribution along the nanowire can be changed via the shell thickness and the gradient of the tapering. Due to the misfit-strain betwee...

N-doped and p-doped GaAs nanowires (NWs) are grown on GaAs (111) B substrate using vapor-liquid-solid (VLS) mechanism via a metalorganic chemical vapor deposition (MOCVD) system. It is found that for n-type doped NWs growth rate is proportional the flux rates of dopant and the structure is pure zinc blende without any faults. For p-type doped NWs w...

Catalyst-free InGaP nanoneedles were grown on Si substrate via metalorganic chemical vapor deposition. From scanning electron microscope (SEM) images, various nanoneedles were observed and the relevant growth mechanism was discussed.

Various surface morphologies of hierarchical GaAs/InAs core/shell heterostructure were obtained by carefully tuning the growth parameters. The growth of the InAs shell around the surface of the GaAs core could be evolved from 2D mode to 3D mode as the variation of the growth parameters. As a consequence, the morphology of the InAs shell can systema...

In this letter, a contact-length-dependent contact resistance model for top-gate staggered organic thin-film transistors (OTFTs) is proposed. The presented model can well describe the contact resistance increase as the distance by which the gate electrode overlaps the source and drain contact (contact length) decrease. Based on the contact resistan...

Vertical GaAs/AlGaAs heterostructure nanowires (NWs) with pure zinc blende structure were grown on Si (111) substrates by using AlGaAs/GaAs buffer layers. Axial and radial heterostructure NWs with different facets can be realized by tuning the growth temperature, so quantum wells with a triangular cross section enclosed by two {112} and one {110} f...

In this letter, high-performance organic phototransistors and photoswitches based on an ultraclosely pi-stacked organic semiconductor, i.e., titanyl phthalocyanine, are fabricated. The p-type transistor exhibited high performance with a hole mobility of similar to 4.5 cm(2) . V-1 . s(-1) and an on/off ratio higher than 3.1 x 10(7). Phototransistors...

This paper presents the design and analysis of a Si-based tunable flattop photodetector realized by the introduction of a stepped Fabry–Perot cavity, which can be thermally tuned via applying tuning power on its tuning electrode. By using a transfer matrix method, the spectral response of the photodetector is simulated in detail, indicating a flatt...

This paper elaborates the design and analysis of a novel monolithically integrated tunable dual-wavelength photodetector which can be formed by heteroepitaxial growth of an InP-based p-i-n absorption structure on a GaAs-based Fabry–Pérot filter. The photodetector presents two response peaks resulting from the introduction of 4-step Fabry–Pérot cavi...

The influence of GaAs substrate on the transmission performance of a multi-film Fabry-Peerot filter (FPF), fabricated by metalorganic chemical vapor deposition epitaxial growth on GaAs substrate, is investigated using the transfer matrix method. On the basis of the theoretical simulation, we determine that the quality of the resonant transmission p...

GaAs/InAs nanowire heterostructures are grown on Si(111) substrate by metal organic chemical vapor deposition via Au-catalyst vapor-liquid-solid mechanism. Nanowires vertical to the substrate are realized by using GaAs/AlGaAs buffer layers. Straight InAs wire is grown axially on the GaAs nanowire by inserting a composition-graded InxGa1-xAs buffer...

InAs quantum dots (QDs) are grown epitaxially on Au-catalyst-grown GaAs nanowires (NWs) by metal organic chemical vapor deposition (MOCVD). These QDs are about 10-30 nm in diameter and several nanometers high, formed on the {112} side facets of the GaAs NWs. The QDs are very dense at the base of the NW and gradually sparser toward the top until dis...

S33 according to the fluorescence threshold, quality of an individual specimen type were evaluated based on the RNase P Ct value. Result: Overall 86 patients suspected Influenza A (H1N1) infection were included in the study between 1 st January and 30 th May 2010. Specimens analyzed included 31 specimens (36.0%) from NPS, 28 specimens (32.6%) from...

A novel resonant-cavity-enhanced (RCE) photodetector based on dual-absorption structure is proposed to optimize the conventional RCE photodetector. Furthermore, its quantum efficiency and high speed response properties are also analyzed theoretically followed by a comparison between the RCE photodetector based on dual-absorption structure and the c...

Vertical zinc blende GaAs/AIGaAs heterostructure nanowires were grown at different temperatures by met-alorganic chemical vapor deposition via Au-assisted vapor-liquid-solid mechanism. It was found that radial growth can be enhanced by increasing the growth temperature. The growth of radial heterostructure can be realized at temperature higher than...

Vertical indium phosphide nanowires (NWs) were grown at different temperatures by metalorganic chemical vapor deposition via a gold (Au)-assisted vapor-liquid-solid mechanism. At a low growth temperature (420 °C), the lengths of the NWs were diameter independent, which indicated that the NWs were grown with significant contributions from the direct...

Pure zinc blende structure GaAs/AlGaAs axial heterostructure nanowires (NWs) are grown by metal organic chemical vapor deposition on GaAs(111) B substrates using Au-catalyzed vapor-liquid-solid mechanism. Al adatom enhances the influence of diameters on NWs growth rate. NWs are grown mainly through the contributions from the direct impingement of t...

Vertical p-type gallium arsenide (GaAs) nanowires with pure zinc blende structure were grown on GaAs (111) B substrate by metal-organic chemical vapor deposition via a Au-catalyst vapor-liquid-solid mechanism. The p-type doping was investigated by additional diethyl zinc (DEZn). In the high II/III ratio range (II/III>9.1%), there exists a critical...

Zinc blende structure GaAs/AlGaAs core-multishell nanowires (NWs) are grown on a GaAs(111) B substrate by a two-temperature process using an Au-catalyzed vapor-liquid-solid mechanism and metal organic chemical vapor deposition, respectively. Defect-free radial heterostructure NWs are formed. It can be concluded that the NWs are grown with the main...

InAs/GaAs and InAs/InxGa1-xAs/GaAs nanowire heterostructures are grown by metal organic chemical vapor deposition via Au-assistant vapor-liquid-solid mechanism. We find that the InAs nanowires grow directly on GaAs nanowires in a random way, or they grow along the sidewall of the GaAs nanowires, and thet InAs nanowires grow vertically on GaAs nanow...

InAs/GaAs and InAs/In xGa1-xAs/GaAs nanowire heterostructures are grown by metal organic chemical vapor deposition via Au-assistant vapor-liquid-solid mechanism. We find that the InAs nanowires grow directly on GaAs nanowires in a random way, or they grow along the sidewall of the GaAs nanowires, and thet InAs nanowires grow vertically on GaAs nano...

Interesting phenomena of GaAs nanowire growth have been observed. The nanowires were grown by metal-organic chemical vapor deposition (MOCVD) on GaAs (1 1 1)B substrates with an Au catalyst at 464 °C. The growth rates of all nanowires were almost the same for a fixed density of Au nanodrops. TEM analysis demonstrates a stacking-fault-free zincblend...

We have designed and fabricated a RCE dual-absorption photodetector. In comparison with conventional ones, our design possesses higher quantum efficiency without imparing other optical properties of the device. In addition, its high speed properties can be obtained.

This paper investigates the influence of the GaAs substrate on the transmission performance of quarter-wave-stacks' Distributed Brag Reflector (DBR)-based Fabry-Pérot (F-P) filter formed by heteroepitaxial growth, using Transfer Matrix Method (TMM) theoretically. According to our simulation, the designed resonant transmission peak of the filter det...

N-doped GaAs nanowires (NWs) were grown on GaAs (111) B substrate by means of vapor-liquid-solid (VLS) mechanism in a metalorganic chemical vapor deposition (MOCVD) system. Two flux rates of n-type dopants used for GaAs NWs growth were researched. For comparison, undoped GaAs NWs were grown at the same conditions. It is found that all NWs are verti...

Vertical p-type Gallium arsenide (GaAs) nanowires with pure zinc blende structure were grown on GaAs (111) B substrate by metal-organic chemical vapor deposition via Au-catalyst vapor-liquid-solid mechanism. The p-type doping was investigated by additional diethyl zinc (DEZn). In high II/III ratio range (II/II>;9.1%), there exists a critical length...

Growth and characterization of GaAs/AlGaAs core-shell nanowires (NWs) are reported. Using the VLS (vapor-liquid-solid) mechanism, GaAs NWs oriented perpendicularly to the substrate were grown on GaAs (111) B substrate. Using the metalorganic chemical vapor deposition (MOCVD) growth mode, AlGaAs shells were grown on GaAs NWs sidewalls. Single crysta...

The effect of temperature on GaAs nanowires (NWs) growth is investigated. Three samples are grown on GaAs (111) B substrate by Au-assisted metalorganic chemical vapor deposition (MOCVD) using vapor-liquid-solid (VLS) mechanism at 500°C, 530°C and 560°C, respectively. It is found that all samples are vertical to the substrate. Their length growth at...

In this paper, analytical method is employed to analyze the system strain energy and critical diameter of one kind of longitudinally heterostructure nanowire which contains component gradient buffer sections. Based on the critical diameter model of F. Glas in heterostructure nonawires, calculation has been made to research on how does single-layer...

The dependence of crystal structure on contributions of adatom diffusion (ADD) and precursor direct impingement (DIM) was investigated for vapor-liquid-solid growth of InAs nanowires (NWs). The ADD contributions from the sidewalls and substrate surface can be changed by using GaAs NWs of different length as the basis for growing InAs NWs. We found...

Pure zinc blende GaAs nanowires were grown by metal organic chemical vapor deposition on GaAs (111) B substrates via Au catalyzed vapor-liquid-solid mechanism. We found that the grown nanowires are rod-like in shape and have a pure zinc blende structure; moreover, the growth rate is independent on its diameters. It can be concluded that, direct imp...

We have investigated the growth and photoluminescence (PL) characteristics of GaAs/AlGaAs core-multishell nanowires (NWs). Theses NWs are grown by means of vapor-liquid-solid (VLS) method for cores growth and metalorganic chemical vapor deposition (MOCVD) for multishell growth on GaAs (111)B substrate. The crystallographic quality is perfect in the...

GaAs nanowires were grown by metal organic chemical vapor deposition on GaAs(111)B substrates via Au catalyzed vapor-liquid-solid mechanism. We found that the grown nanowires are rode-like shape and the growth rate is independent on its diameters. It can be concluded that the nanowire was grown with main contributions from direct impingement of vap...

Pure zinc blende GaAs nanowires were grown by metal organic chemical vapor deposition on GaAs(111)B substrates via Au catalyzed vapor-liquid-solid mechanism. The diameter, size distribution, and density of Au particles can be changed by varying the Au film thickness. We find that the grown nanowires are of rod-like shapes and pure zinc blende struc...

Vertical GaAs nanowires on Si (111) substrate were grown by metal organic chemical vapor deposition via Au-catalyst vapor-liquid-solid mechanism. Stacking-faults-free zinc blende nanowires were realized by using AlGaAs/GaAs buffer layers and growing under the optimized conditions, that the alloy droplet act as a catalyst rather than an adatom colle...

InP nanowires were grown on InP(100) substrates via VLS mechanism with Au particles as catalyst. Various morphologies of the nanowires such as straight, L-branch, Y-branch, K-branch, bottle-shape, cone-shape, needle-shape were obtained.