Growth of InAs nanowires on SiO2 substrates:: Nucleation, evolution, and the role of an nanoparticles

We have studied the nucleation and growth of InAs nanowires (NWs) on SiO2/Si substrates by organometallic vapor-phase epitaxy (OMVPE). Through systematic characterization of InAs NW morphology as a function of V/III precursor ratio, precursor flow rates, growth temperature, growth time, and the presence/absence of An nanoparticles, a number of significant insights into InAs NW growth using OMVPE have been developed. Specifically, we have found that (i) the growth of InAs NWs can be initiated from a single indium (In) droplet, (ii) An nanoparticles (NPs) enhance group V precursor (AsH3) pyrolysis but are not necessary to nucleate growth, (iii) growth of InAs NWs on SiO2 substrates occurs in the kinetically limited vapor-liquid-solid (VLS) growth regime, (iv) InAs NWs on SiO2 films decompose at elevated temperatures even under significant AsH3 overpressure, and (v) the V/III ratio is the growth-rate-limiting factor in the VLS growth of the InAs nanowires. Many of these findings on InAs NW growth can be generalized to and provide very useful information for rational synthesis of other III-V compound semiconductor NWs.