Recipes for crystal phase design in Au-catalyzed III-V nanowires

Abstract

We develop a kinetic model for the crystal structure of Au-catalyzed III-V nanowires which is capable of describing the wurtzite content as a function of the growth temperature, group V flux, and the nanowire elongation rate. The self-consistency condition with the correct pre-exponent in the Zeldovich nucleation rate allows us to estimate the actual group III concentration in the droplet which corresponds to a given elongation rate. Our model predicts a non-monotonic dependence of the wurtzite percentage on the group III concentration. We analyze relevant experimental data on the preferred crystal structure of Au-catalyzed GaAs nanowires obtained by three different epitaxy techniques and explain why the MBE-grown GaAs nanowires at near 550°C are predominantly wurtzite, while the MOCVD and HVPE-grown GaAs nanowires obtained with very high As fluxes and at very different temperatures (464°C and 715°C) are zincblende. Overall, the model provides some simple recipes for structural design of III-V nanowires by tuning the technologically controlled growth conditions such as temperature and fluxes.