Thermal decomposition of GaAs nanowires

Abstract

The realization of GaAs nanowire (NW) high-performance quantum devices operated at room temperatures requires that their diameters have to be less than 10 nm. It is shown, that the GaAs NWs with sub 10 nanometers diameters can be fabricated using the thermal decomposition technique. It is demonstrated, that depending on annealing conditions, the NW lengths, as well as shapes, can be modified significantly. The GaAs NWs with bottle-like and diameter-modulated shapes can be obtained. At the first stage of the thermal annealing in the presence of As flux, an increase in NW length was found.

Real-time thermal decomposition kinetics of GaAs nanowires and their crystal polytypes on the atomic scale

“…Similar abrupt changes in length have been observed for decomposition in similar NW systems, where even extended (hundreds of nm long) segments of small diameter abruptly disappear because the diameter gets too small. 23,31 In order to investigate if the effect of increasing decomposition rate for smaller diameters also applies to radial decomposition, we take a close look at the radial decomposition rates throughout different stages of the decomposition experiment. However, care needs to be taken in the analysis, because decomposition rates at different times may not be directly related to geometric parameters only, due to the imperfect stability of the local temperature.…”

“…Similar abrupt changes in length have been observed for decomposition in similar NW systems, where even extended (hundreds of nm long) segments of small diameter abruptly disappear because the diameter gets too small. 23,31…”

“…Nevertheless, basic studies of in situ decomposition and ex situ analysis were applied to e.g. , GaN, 28,29 GaAs 22,31 and InAs 23 NWs and it was shown that their diameters could be reduced to sub-20 nm dimensions, enabling the observation of 1D quantum confinement effects.…”

“…Hereby, two main approaches can be distinguished, each coming with certain compromises: rst, decomposition experiments within the epitaxial growth environment inside the growth reactor, combined with ex situ analysis, usually by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). 22,23,[28][29][30][31] And, secondly, conventional growth of NWs combined with subsequent transfer for ex situ decomposition and analysis, mostly by heating NWs inside a TEM. [32][33][34][35] The rst approach enables best quality of the NWs because contamination and oxidation of the surfaces is prevented.…”

Controlled Synthesis of Pure-Phase GaAs Nanowires through Shear Tension

“…Therefore, controlling or eliminating the perturbation is an effective way to achieve the perfect single-phase GaAs NWs. Up until now, the fabrication of pure-phase NWs has been realized by precise regulation of parameters during growth, such as growth temperature, − V/III flux ratio, , droplet shape, − annealing temperature, , epitaxial burying, and doping. ,− Researchers control the energy perturbation through seeking an appropriate growth window. However, the successful fabrication of the pure-phase structure by the above methods is complicated due to the small growth window and difficult control.…”