Growth of Nanowires on GaAs (100) Substrate

Abstract

<p> Using gold as seed particles, the vapour-liquid-solid (VLS) growth of GaAs nanowires by molecular beam epitaxy on GaAs (100) substrates was investigated with a view to understanding and controlling the growth directions of nanowires. The crystallographic orientation as well as surface density of nanowires was found to be significantly affected by surface topography resulting from surface preparation prior to nanowire growth. Elongated pits of varying dimensions and orientation were formed on GaAs (100) substrates depending on the interaction of GaAs with gold or surface oxide. An in-depth analysis was carried out regarding the formation of pits as well as chemical composition of the oxide layer during the seed particle formation process. </p> <p> By analyzing the orientation-dependent structural properties of nanowires at different stages of growth, the origin of multi-directionality of nanowires on GaAs (100) substrates has been explored, and it has been shown that the growth directionality of nanowires can be significantly triggered to either the <011> or <111> direction by optimizing the growth rate as well as size of seed particles. Crystallographic properties of nanowires have also been discussed with reference to their growth directions.</p>