  High aspect ratio, rod-like and single crystal phase GaAs nanowires (NWs)
were grown by gold catalyst-assisted hydride vapor phase epitaxy (HVPE). High
resolution transmission electron microscopy (HRTEM) and micro-Raman
spectroscopy revealed polytypism-free zinc blende NWs over lengths of several
tens of micrometers for diameters ranging between 50 and 150 nm.
Micro-photoluminescence studies of individual NWs showed linewidths smaller
than those reported elsewhere which is consistent with the crystalline quality
of the NWs. HVPE makes use of chloride growth precursors of which high
decomposition frequency, after adsorption onto the catalyst particle, favors a
direct and rapid introduction of the Ga atoms from the vapor phase into the
catalyst liquid droplet. This yields high axial growth rate (more than 100
micron/h) of NWs. The fast diffusion of the Ga atoms in the droplet towards the
interface between the liquid and the solid nanowire was investigated by using
density functional theory calculations. The diffusion coefficient of Ga atoms
was estimated to be 3x10-9 m2/s, which matches the experimental observations.
