scholarly journals Highly tuneable hole quantum dots in Ge-Si core-shell nanowires

2016 ◽  
Vol 109 (14) ◽  
pp. 143113 ◽  
Author(s):  
Matthias Brauns ◽  
Joost Ridderbos ◽  
Ang Li ◽  
Wilfred G. van der Wiel ◽  
Erik P. A. M. Bakkers ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Core Shell ◽  
Shell Nanowires

Crystal Phase Quantum Dots in the Ultrathin Core of GaAs–AlGaAs Core–Shell Nanowires

Nano Letters ◽  
2015 ◽  
Vol 15 (11) ◽  
pp. 7544-7551 ◽  
Author(s):  
Bernhard Loitsch ◽  
Julia Winnerl ◽  
Gianluca Grimaldi ◽  
Jakob Wierzbowski ◽  
Daniel Rudolph ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Crystal Phase ◽  
Core Shell ◽  
Shell Nanowires

scholarly journals Exciton footprint of self-assembled AlGaAs quantum dots in core-shell nanowires

2014 ◽  
Vol 90 (7) ◽  
Author(s):  
Yannik Fontana ◽  
Pierre Corfdir ◽  
Barbara Van Hattem ◽  
Eleonora Russo-Averchi ◽  
Martin Heiss ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Core Shell ◽  
Self Assembled ◽  
Shell Nanowires

scholarly journals Exciton dynamics in GaAs/(Al,Ga)As core-shell nanowires with shell quantum dots

2016 ◽  
Vol 94 (15) ◽  
Author(s):  
Pierre Corfdir ◽  
Hanno Küpers ◽  
Ryan B. Lewis ◽  
Timur Flissikowski ◽  
Holger T. Grahn ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Core Shell ◽  
Exciton Dynamics ◽  
Shell Nanowires

scholarly journals Quantum dots in the GaAs/AlxGa1−xAs core-shell nanowires: Statistical occurrence as a function of the shell thickness

2015 ◽  
Vol 107 (3) ◽  
pp. 033106 ◽  
Author(s):  
Luca Francaviglia ◽  
Yannik Fontana ◽  
Sonia Conesa-Boj ◽  
Gözde Tütüncüoglu ◽  
Léo Duchêne ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Shell Thickness ◽  
Core Shell ◽  
Shell Nanowires

scholarly journals Modeling of the growth of GaAs–AlGaAs core–shell nanowires

2017 ◽  
Vol 8 ◽  
pp. 506-513 ◽  
Author(s):  
Qian Zhang ◽  
Peter W Voorhees ◽  
Stephen H Davis
Keyword(s):  
Quantum Dots ◽  
High Performance ◽  
Morphological Evolution ◽  
Shell Morphology ◽  
Core Shell ◽  
Attachment Rate ◽  
Wire Cross Section ◽  
The Difference ◽  
Facet Size ◽  
Shell Nanowires

Heterostructured GaAs–AlGaAs core–shell nanowires with have attracted much attention because of their significant advantages and great potential for creating high performance nanophotonics and nanoelectronics. The spontaneous formation of Al-rich stripes along certain crystallographic directions and quantum dots near the apexes of the shell are observed in AlGaAs shells. Controlling the formation of these core–shell heterostructures remains challenging. A two-dimensional model valid on the wire cross section, that accounts for capillarity in the faceted surface limit and deposition has been developed for the evolution of the shell morphology and concentration in Al x Ga1− x As alloys. The model includes a completely faceted shell–vapor interface. The objective is to understand the mechanisms of the formation of the radial heterostructures (Al-rich stripes and Al-poor quantum dots) in the nanowire shell. There are two issues that need to be understood. One is the mechanism responsible for the morphological evolution of the shells. Analysis and simulation results suggest that deposition introduces facets not present on the equilibrium Wulff shapes. A balance between diffusion and deposition yields the small facets with sizes varying slowly over time, which yield stripe structures, whereas deposition-dominated growth can lead to quantum-dot structures observed in experiments. There is no self-limiting facet size in this case. The other issue is the mechanism responsible for the segregation of Al atoms in the shells. It is found that the mobility difference of the atoms on the {112} and {110} facets together determine the non-uniform concentration of the atoms in the shell. In particular, even though the mobility of Al on {110} facets is smaller than that of Ga, Al-rich stripes are predicted to form along the {112} facets when the difference of the mobilities of Al and Ga atoms is sufficiently large on {112} facets. As the size of the shell increases, deposition becomes more important. The Al-poor dots are obtained at the apices of {112} facets, if the attachment rate of Al atoms is smaller there.

Study of nanometer-scale structures and electrostatic properties of InAs quantum dots decorating GaAs/AlAs core/shell nanowires

2020 ◽  
Vol 31 (24) ◽  
pp. 245701
Author(s):  
Tianyu Qi ◽  
Yongfa Cheng ◽  
Feng Cheng ◽  
Luying Li ◽  
Chen Li ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Nanometer Scale ◽  
Core Shell ◽  
Inas Quantum Dots ◽  
Electrostatic Properties ◽  
Scale Structures ◽  
Shell Nanowires

High-Temperature Synthesis of CdSe-Based Core/Shell, Core/Shell/Shell, and Core/Graded-Shell Nanoplatelets for Stable and Efficient Narrowband Emitters

2019 ◽  
Author(s):  
Aurelio A. Rossinelli ◽  
Henar Rojo ◽  
Aniket S. Mule ◽  
Marianne Aellen ◽  
Ario Cocina ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Temperature ◽  
Equilibrium Shape ◽  
Size Variation ◽  
Crystal Defects ◽  
Atomic Scale ◽  
Quantum Yields ◽  
Core Shell ◽  
Compositional Gradient ◽  
High Quality

<div>Colloidal semiconductor nanoplatelets exhibit exceptionally narrow photoluminescence spectra. This occurs because samples can be synthesized in which all nanoplatelets share the same atomic-scale thickness. As this dimension sets the emission wavelength, inhomogeneous linewidth broadening due to size variation, which is always present in samples of quasi-spherical nanocrystals (quantum dots), is essentially eliminated. Nanoplatelets thus offer improved, spectrally pure emitters for various applications. Unfortunately, due to their non-equilibrium shape, nanoplatelets also suffer from low photo-, chemical, and thermal stability, which limits their use. Moreover, their poor stability hampers the development of efficient synthesis protocols for adding high-quality protective inorganic shells, which are well known to improve the performance of quantum dots. <br></div><div>Herein, we report a general synthesis approach to highly emissive and stable core/shell nanoplatelets with various shell compositions, including CdSe/ZnS, CdSe/CdS/ZnS, CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S, and CdSe/ZnSe. Motivated by previous work on quantum dots, we find that slow, high-temperature growth of shells containing a compositional gradient reduces strain-induced crystal defects and minimizes the emission linewidth while maintaining good surface passivation and nanocrystal uniformity. Indeed, our best core/shell nanoplatelets (CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S) show photoluminescence quantum yields of 90% with linewidths as low as 56 meV (19.5 nm at 655 nm). To confirm the high quality of our different core/shell nanoplatelets for a specific application, we demonstrate their use as gain media in low-threshold ring lasers. More generally, the ability of our synthesis protocol to engineer high-quality shells can help further improve nanoplatelets for optoelectronic devices.</div>

One-Dimensional TiO2@GaON Core-Shell Nanowires with Controlled Shell Thickness from Atomic Layer Deposition for Stable and Efficient Photoelectrochemical Water Splitting

2019 ◽  
Author(s):  
Jiajia Tao ◽  
Hong-Ping Ma ◽  
Kaiping Yuan ◽  
Yang Gu ◽  
Jianwei Lian ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Band Gap ◽  
Water Splitting ◽  
Atomic Layer ◽  
Photoelectrochemical Water Splitting ◽  
Core Shell ◽  
Photoelectrochemical Performance ◽  
Highly Efficient ◽  
Layer Deposition ◽  
Shell Nanowires

<div>As a promising oxygen evolution reaction semiconductor, TiO2 has been extensively investigated for solar photoelectrochemical water splitting. Here, a highly efficient and stable strategy for rationally preparing GaON cocatalysts on TiO2 by atomic layer deposition is demonstrated, which we show significantly enhances the</div><div>photoelectrochemical performance compared to TiO2-based photoanodes. For TiO2@20 nm-GaON core-shell nanowires a photocurrent density up to 1.10 mA cm-2 (1.23 V vs RHE) under AM 1.5 G irradiation (100 mW cm-2) has been achieved, which is 14 times higher than that of TiO2 NWs. Furthermore, the oxygen vacancy formation on GaON as well as the band gap matching with TiO2 not only provides more active sites for water oxidation but also enhances light absorption to promote interfacial charge separation and migration. Density functional theory studies of model systems of GaON-modified TiO2 confirm the band gap reduction, high reducibility and ability to activate water. The highly efficient and stable systems of TiO2@GaON core-shell nanowires provide a deeper understanding and universal strategy for enhancing photoelectrochemical performance of photoanodes now available. </div>

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