On the Luminescence of VLS-grown GaAs-AlGaAs Core-Shell Nanowires and its Dependence on MOVPE Growth Conditions

2009 ◽  
Vol 1206 ◽  
Author(s):  
Paola Prete ◽  
Nico Lovergine ◽  
Ilio Miccoli ◽  
Fabio Marzo ◽  
Joan S. Burger ◽  
...  
Keyword(s):  
Space Charge ◽  
Space Charge Region ◽  
Growth Conditions ◽  
Molar Ratio ◽  
Core Shell ◽  
The Core ◽  
Movpe Growth ◽  
Gaas Nanowire ◽  
Pl Emission ◽  
Shell Nanowires

AbstractWe report on the photoluminescence (PL) of GaAs-Al0.32Ga0.68As core-shell nanowires grown by MOVPE, and their dependence on the precursors V:III molar ratio utilised in the vapor during growth. It is shown that the PL emission of the GaAs nanowire core red-shifts with decreasing the V:III ratio from 30:1 to 4:1, an effect tentatively ascribed to the build-up of a space-charge region at the core-shell hetero-interface, the latter associated to the unintentional incorporation of impurities, namely C in GaAs and Si in AlGaAs.

scholarly journals On the Luminescence of VLS-grown GaAs-AlGaAs Core-Shell Nanowires and its Dependence on MOVPE Growth Conditions - CORRIGENDUM

MRS Advances ◽  
2020 ◽  
Vol 5 (64) ◽  
pp. 3565-3565
Author(s):  
Paola Prete ◽  
Nico Lovergine ◽  
Ilio Miccoli ◽  
Fabio Marzo ◽  
Joan S. Burger ◽  
...  
Keyword(s):  
Growth Conditions ◽  
Core Shell ◽  
Movpe Growth ◽  
Shell Nanowires

Synthesis of CdTe and CdTe/CdS Core-Shell Quantum Dots and their Optical Properties

2011 ◽  
Vol 306-307 ◽  
pp. 1350-1353 ◽  
Author(s):  
Juan Juan Lu ◽  
Shen Guang Ge ◽  
Fu Wei Wan ◽  
Jing Hua Yu
Keyword(s):  
Quantum Dots ◽  
Thioglycolic Acid ◽  
Water Soluble ◽  
Molar Ratio ◽  
Core Shell ◽  
The Core ◽  
Cdte Qds ◽  
Quality Water ◽  
Synthesis Procedure ◽  
Pl Emission

This paper describes the synthesis of CdTe and CdTe/CdS core-shell quantum dots (QDs) in aqueous solution. The quantum dots are prepared by using thioglycolic acid (TGA) as stabilizers. The synthesis procedure is simple and controllable. Different sized CdTe QDs with tuned PL wavelengths from 550 to 640 nm was synthesized by controlling reaction time within 5 h in aqueous solutions at a temperature of 100 °C. We also investigated the influence of precursor Cd/Te molar ratio for the prepared QDs. It was showed that the core-shell CdTe/CdS QDs have larger photoluminescence (PL) emission intensity than the original CdTe QDs. The synthesized core-shell CdTe/ZnS QDs have high quality, water-soluble and will be useful in applications of biolabeling, biosensing, and imaging.

Regulating the electronic and optical properties of GaN/InN core/shell nanowires: A first-principles study

2020 ◽  
Vol 34 (25) ◽  
pp. 2050214 ◽  
Author(s):  
Chang Liu ◽  
Enling Li ◽  
Tuo Peng ◽  
Kaifei Bai ◽  
Yanpeng Zheng ◽  
...  
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Core Shell ◽  
First Principles Calculations ◽  
Electronic And Optical Properties ◽  
Gan Nanowires ◽  
The Core ◽  
Light Region ◽  
Calculation Results ◽  
Shell Nanowires

In this paper, electronic and optical properties of GaN/InN core/shell nanowires (CSNWs) have been theoretically investigated through the first principles calculations. The binding energy of In and N atoms on surface of six crystal planes along the [Formula: see text]-axis of GaN nanowires are all negative, which indicate that In and N atoms can be effectively deposited on the surface of GaN nanowires and preparing GaN/InN CSNWs is feasible theoretically. Calculation results of electronic properties indicate that the core/shell ratio and diameter of GaN/InN CSNWs have significant effect on the band structure, bandgap can be effectively adjusted when keeping the number of GaN layers unchanged and changing the number of InN layers. Moreover, with the increase in the number of InN layers, the absorption spectrum of GaN/InN CSNW has significant redshift and few weak absorption peaks appear in the visible light region.

Synthesis of Core-Shell Composite of Conductive Polymeric Materials onto Silica Using Supercritical Carbon Dioxide

MRS Advances ◽  
2020 ◽  
Vol 5 (40-41) ◽  
pp. 2121-2127
Author(s):  
Ssu-Hao Huang ◽  
Pei-Hua Chen ◽  
Yan-Ping Chen ◽  
Muoi Tang
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Polymeric Materials ◽  
Optimal Operation ◽  
Molar Ratio ◽  
Core Shell ◽  
The Core ◽  
Operation Conditions ◽  
Shell Composite ◽  
Supercritical Carbon

ABSTRACTThe polymerization of 3,4-ethylenedioxythiophene (EDOT) onto nanosilica (SiO2) was synthesized in this study by using supercritical carbon dioxide (SCCO2). With the addition of dopants of p-toluenesulfonic acid (p-TSA) or decylbenzene sulfonic acid (DBSA), the PEDOT/SiO2 composite became conductive. The product was characterized by FTIR spectroscopy and the core-shell structure was confirmed through the TEM images. The electrical properties were analyzed by UV-vis absorbance and four-point probe measurement. DBSA is shown as the better dopants with the molar ratio (DBSA/EDOT) of 0.2 at the reaction time of 48 hours. The maximum coating percentage is 63 wt% under the optimal operation conditions at 40oC and 280 bar. The conductivity is tuned up to 6.6×10-2 S/cm after the coating process.

Ferromagnetic ZnO-TiO2 Core-Shell Nanowire PhotoCatalyst with High Efficiency and Recyclability

2011 ◽  
Vol 90-93 ◽  
pp. 1702-1705
Author(s):  
Xi Zhang ◽  
Gang Xiang
Keyword(s):  
High Efficiency ◽  
Hole Concentration ◽  
Band Gaps ◽  
The Other ◽  
Band Edge ◽  
Core Shell ◽  
Hole Density ◽  
The Core ◽  
Recyclable Photocatalyst ◽  
Shell Nanowires

We demonstrate the design of the recyclable photocatalyst based on ferromagnetic (FM) ZnO- TiO2 core-shell nanowires (NWs). Since the band gaps and band edge energies of bulk ZnO and anatase TiO2 are equal to each other within about 45mV, TiO2 and ZnO can form an p-p+ heterojunction free of band discontinuities and with a built-in potential. The resulting radial field will increase hole density in the TiO2 layer while reduce hole concentration at the interface between the core and the shell, which in turn will decrease the rate of recombination in the photocatalytic TiO2, and hence increase the efficiency of photocatalyst. On the other hand, the NWs with FM cores can be easily collected and refreshed using solenoid and suitable for the recyclable usage of the NW catalyst

EFFECT OF ELECTRIC FIELD, TEMPERATURE AND CORE DIMENSIONS IN III–V COMPOUND CORE–SHELL NANOWIRES

NANO ◽  
2014 ◽  
Vol 09 (04) ◽  
pp. 1450051
Author(s):  
ASHWANI VERMA ◽  
BAHNIMAN GHOSH ◽  
AKSHAY KUMAR SALIMATH
Keyword(s):  
Monte Carlo ◽  
Electric Field ◽  
Spin Relaxation ◽  
Compound Semiconductor ◽  
Core Shell ◽  
Relaxation Length ◽  
The Core ◽  
Field Temperature ◽  
Simulation Results ◽  
Shell Nanowires

In this paper, we have used semiclassical Monte Carlo method to show the dependence of spin relaxation length in III–V compound semiconductor core–shell nanowires on different parameters such as lateral electric field, temperature and core dimensions. We have reported the simulation results for electric field in the range of 0.5–10 kV/cm, temperature in the range of 77–300 K and core length ranging from 2 nm to 8 nm. The spin relaxation mechanisms used in III–V compound semiconductor core–shell nanowire are D'yakonov–Perel (DP) relaxation and Elliott–Yafet (EY) relaxation. Depending upon the choice of materials for core and shell, nanowire forms two types of band structures. We have used InSb – GaSb core–shell nanowire and InSb – GaAs core–shell nanowire and nanowire formed by swapping the core and shell materials to show all the results.

scholarly journals Silica Coating of Metal-Loaded H-ZSM-22 to Form the Core-Shell Nanostructures: Characterization, Textural Properties, and Catalytic Potency in the Esterification of Oleic Acid

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Maryam Haghighi ◽  
Mehranoosh Fereidooni
Keyword(s):  
Oleic Acid ◽  
Electron Microscope ◽  
Active Sites ◽  
Maximum Yield ◽  
Operating Conditions ◽  
Molar Ratio ◽  
Emission Spectrometry ◽  
Esterification Reaction ◽  
Core Shell ◽  
The Core

In this study, ZSM-22 was synthesized using N,N-diethylaniline as a template through a hydrothermal method. The proton and various metals such as zirconium, strontium, and iron were immobilized on the surface of obtained zeolites through the ion exchange method. The catalysts were studied by Fourier-Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption isotherms, Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) elemental analysis, and Temperature-Programmed Desorption of ammonia (TPD-NH3) technique for determining the number of acid sites. In the esterification reaction of oleic acid, the operating conditions such as catalyst dosage, temperature, molar ratio of methanol to oil, and reaction time were optimized and adjusted at 11 wt%, 70°C, 10 : 1, and 48 h subsequently. The maximum yield% of 48.07% was achieved in the presence of Zr-H-ZSM-22 at optimum conditions. In order to improve the efficiency of three zeolites Zr-H-ZSM-22, Fe-H-ZSM-22, and Sr-H-ZSM-22, the core-shell structures with SiO2 coating were prepared. Zr-H-ZSM-22@SiO2 was less active than Zr-H-ZSM-22 due to the SiO2 coverage of Lewis active sites.

scholarly journals Facet-Related Non-uniform Photoluminescence in Passivated GaAs Nanowires

2020 ◽  
Vol 8 ◽  
Author(s):  
Nian Jiang ◽  
Hannah J. Joyce ◽  
Patrick Parkinson ◽  
Jennifer Wong-Leung ◽  
Hark Hoe Tan ◽  
...  
Keyword(s):  
Significant Variation ◽  
Volume Ratio ◽  
Gaas Layer ◽  
Core Shell ◽  
Strongly Correlated ◽  
Semiconductor Nanowire ◽  
Gaas Nanowires ◽  
Pl Emission ◽  
Nanowire Device ◽  
Shell Nanowires

The semiconductor nanowire architecture provides opportunities for non-planar electronics and optoelectronics arising from its unique geometry. This structure gives rise to a large surface area-to-volume ratio and therefore understanding the effect of nanowire surfaces on nanowire optoelectronic properties is necessary for engineering related devices. We present a systematic study of the non-uniform optical properties of Au-catalyzed GaAs/AlGaAs core–shell nanowires introduced by changes in the sidewall faceting. Significant variation in intra-wire photoluminescence (PL) intensity and PL lifetime (τPL) was observed along the nanowire axis, which was strongly correlated with the variation of sidewall facets from {112} to {110} from base to tip. Faster recombination occurred in the vicinity of {112}-oriented GaAs/AlGaAs interfaces. An alternative nanowire heterostructure, the radial quantum well tube consisting of a GaAs layer sandwiched between two AlGaAs barrier layers, is proposed and demonstrates superior uniformity of PL emission along the entire length of nanowires. The results emphasize the significance of nanowire facets and provide important insights for nanowire device design.

Mechanical properties of Ge/Si core-shell nanowires under a uniaxial tension

2006 ◽  
Vol 958 ◽  
Author(s):  
Y. Yano ◽  
T. Nakajima ◽  
K. Shintani
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Single Atom ◽  
Core Shell ◽  
The Core ◽  
Young’S Moduli ◽  
Vegard’S Law ◽  
Shell Nanowires

ABSTRACTThe mechanical properties of Si/Ge core-shell nanowires under a unixial tension are studied using molecular-dynamics simulation. The effects of anisotropy and the fraction of the core atoms on the Young's moduli of the core-shell nanowires are examined. The values of their Young's moduli deviate from those calculated using Vegard's law. Single atom chains are formed at the final stages of elongation of the nanowires.

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