Growth kinetics of GaAs nanoneedles on silicon and sapphire substrates

Abstract

We study theoretically and experimentally the time evolution of GaAs nanoneedles grown by metal organic chemical vapor deposition on silicon and sapphire substrates. A theoretical model is presented which provides explicitly the nanoneedle length as a function of growth time under the assumption of a fixed aspect ratio. Experimental data confirms that the aspect ratio remains approximately constant during the growth. From fitting the experimental length-time dependences, we estimate the effective arrival rates and the Ga diffusion lengths as being 3.5 nm/min and 80 nm on the silicon and 2.9 nm/min and 400 nm on the sapphire substrates, respectively.