Manipulated Growth of GaAs Nanowires: Controllable Crystal Quality and Growth Orientations via a Supersaturation-Controlled Engineering Process

Abstract

Controlling the crystal quality and growth orientation of high performance III–V compound semiconductor nanowires (NWs) in a large-scale synthesis is still challenging, which could restrict the implementation of nanowires for practical applications. Here we present a facile approach to control the crystal structure, defects, orientation, growth rate and density of GaAs NWs via a supersaturation-controlled engineering process by tailoring the chemical composition and dimension of starting Au x Ga y catalysts. For the high Ga supersaturation (catalyst diameter < 40 nm), NWs can be manipulated to grow unidirectionally along ⟨111⟩ with the pure zinc blende phase with a high growth rate, density and minimal amount of defect concentration utilizing the low-melting-point catalytic alloys (AuGa, Au2Ga, and Au7Ga3 with Ga atomic concentration > 30%), whereas for the low Ga supersaturation (catalyst diameter > 40 nm), NWs are grown inevitably with a mixed crystal orientation and high concentration of defects from high-melting-point alloys (Au7Ga2 with Ga atomic concentration < 30%). In addition to the complicated control of processing parameters, the ability to tune the composition of catalytic alloys by tailoring the starting Au film thickness demonstrates a versatile approach to control the crystal quality and orientation for the uniform NW growth.

Surfactant-assisted chemical vapour deposition of high-performance small-diameter GaSb nanowires

“…Realistically, during the growth process, it is inevitable that Ga will also be surface-diffused from the NW base and reacted with the surface-terminated Sb, contributing to the unintentional radial (VS) NW growth (red arrow); as a result, the tapering and non-uniform NW diameter (white circle) are obtained (Fig. 5b,c), as commonly found in other III-V NW growth 9,[40][41][42][43][44] . With the aid of sulfur surfactant passivating these surface active Sb sites, the NW sidewall is stabilized (red arrow) and minimal uncontrolled radial growth results (Fig.…”

“…Although significant progress has been made in the manipulation of NW nucleation and composition in both binary and ternary systems 9,10 , it is still challenging to control the morphology and size of NWs on length scales ranging from the atomic upwards, particularly for the technologically important III-Sb NWs. In general, the growth of III-Sb NWs has proven difficult from small-diameter catalyst particles in various chemical vapour deposition (CVD) techniques [11][12][13] and others, yielding larger diameters than the corresponding III-As NWs [14][15][16] .…”

GaAs nanowires grown on Al-doped ZnO buffer layer

“…Furthermore, Ga supersaturation has been reported to affect the phase of the Au-Ga alloy and hence the crystal structure of the resulting NWs. 32 When Zn is present in the seed particle, the alloy becomes Au-Ga-Zn, which might further alter the phase of the seed particle. The presence of Zn is thus expected to affect the delicate growth process of the NWs.…”

Recent advances in the growth of germanium nanowires: synthesis, growth dynamics and morphology control

“…In other words, the time frame over which the precursor is injected into the system in a typical CVD set-up determines the length of the resulting nanowires and is logical because when the injection stops, there is no longer any incorporation of the semiconductor material into the nanowire and therefore growth discontinues. Other methods of tuning the length of nanowires may involve manipulating the kinetics at the liquid-solid interface via the supersaturation of the metal seed particle 70,198 . Dubrovskii et al have demonstrated the narrowing of the length distribution of Ge nanowires and also presented a theoretical model to explain the behaviour 197 .…”