Structural analysis of self-catalyzed GaAs nanowires (NWs) grown on lithography-free oxide patterns is described with insight on their growth kinetics. Statistical analysis of templates and NWs in different phases of the growth reveals extremely high-dimensional uniformity due to a combination of uniform nucleation sites, lack of secondary nucleation of NWs, and self-regulated growth under the effect of nucleation antibunching. Consequently, we observed the first evidence of sub-Poissonian GaAs NW length distributions. The high phase purity of the NWs is demonstrated using complementary transmission electron microscopy (TEM) and high-resolution X-ray diffractometry (HR-XRD). It is also shown that, while NWs are to a large extent defect-free with up to 2-μm-long twin-free zincblende segments, low-temperature micro-photoluminescence spectroscopy reveals that the proportion of structurally disordered sections can be detected from their spectral properties.
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http://dx.doi.org/10.1186/s11671-017-1989-9 | DOI Listing |
ACS Nano
August 2024
Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden 01328, Germany.
As semiconductor devices approach dimensions at the atomic scale, controlling the compositional grading across heterointerfaces becomes paramount. Particularly in nanowire axial heterostructures, which are promising for a broad spectrum of nanotechnology applications, the achievement of sharp heterointerfaces has been challenging owing to peculiarities of the commonly used vapor-liquid-solid growth mode. Here, the grading of Al across GaAs/AlGaAs/GaAs heterostructures in self-catalyzed nanowires is studied, aiming at finding the limits of the interfacial sharpness for this technologically versatile material system.
View Article and Find Full Text PDFNanoscale Adv
March 2023
Research Center for Integrated Quantum Electronics, Hokkaido University Sapporo 060-0813 Japan
GaAs/AlGaAs core-shell nanowires, typically having 250 nm diameter and 6 μm length, were grown on 2-inch Si wafers by the single process of molecular beam epitaxy using constituent Ga-induced self-catalysed vapor-liquid-solid growth. The growth was carried out without specific pre-treatment such as film deposition, patterning, and etching. The outermost Al-rich AlGaAs shells form a native oxide surface protection layer, which provides efficient passivation with elongated carrier lifetime.
View Article and Find Full Text PDFNanomaterials (Basel)
May 2022
Peter the Great St. Petersburg Polytechnic University, Polytechnicheskaya St. 29, 195251 St. Petersburg, Russia.
A new model for the radial growth of self-catalyzed III-V nanowires on different substrates is presented, which describes the nanowire morphological evolution without any free parameters. The model takes into account the re-emission of group III atoms from a mask surface and the shadowing effect in directional deposition techniques such as molecular beam epitaxy. It is shown that radial growth is faster for larger pitches of regular nanowire arrays or lower surface density, and can be suppressed by increasing the V/III flux ratio or decreasing re-emission.
View Article and Find Full Text PDFNanotechnology
May 2022
Nanoengineering, Joint School of Nanoscience and Nanoengineering, North Carolina A&T State University, Greensboro NC, 27401, United States of Americ a.
This work evaluates the passivation efficacy of thermal atomic layer deposited (ALD) AlOdielectric layer on self-catalyzed GaAsSbnanowires (NWs) grown using molecular beam epitaxy. A detailed assessment of surface chemical composition and optical properties of AlOpassivated NWs with and without prior sulfur treatment were studied and compared to as-grown samples using x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and low-temperature photoluminescence (PL) spectroscopy. The XPS measurements reveal that prior sulfur treatment followed by AlOALD deposition abates III-V native oxides from the NW surface.
View Article and Find Full Text PDFNanoscale Horiz
February 2022
Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, UK.
Embedding quantum dots (QDs) on nanowire (NW) sidewalls allows the integration of multi-layers of QDs into the active region of radial p-i-n junctions to greatly enhance light emission/absorption. However, the surface curvature makes the growth much more challenging compared with growths on thin-films, particularly on NWs with small diameters (Ø < 100 nm). Moreover, the {110} sidewall facets of self-catalyzed NWs favor two-dimensional growth, with the realization of three-dimensional Stranski-Krastanow growth becoming extremely challenging.
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