Control of GaAs nanowire morphology by group III precursor chemistry

Abstract

In this work we show that the choice of Ga precursors has a striking effect on the growth kinetics of GaAs nanowires grown by metalorganic vapor phase epitaxy (MOVPE) using the vapor–liquid–solid (VLS) growth mechanism. We investigate the detailed temperature dependence of nanowire axial and lateral growth rates using two different Ga sources, trimethylgallium (TMGa) and triethylgallium (TEGa), in conjunction with tertiarybutylarsine. We observed dramatically enhanced tapering for TEGa compared with TMGa, which is attributed to lateral growth resulting from a much lower decomposition temperature of TEGa. For both precursors, the competition between vapor–solid (VS) and VLS surface reaction rates is the primary determinant of nanowire morphology. The results show strong evidence of the catalytic effect of Au on the total mass growth rate for the case of TMGa growth. We demonstrate the usefulness of precursor chemistry in controlling InAs/GaAs heterostructure growth. Axial InAs/GaAs heterostructures were grown using trimethylindium (TMIn) and TMGa. In contrast, core–shell InAs/GaAs heterostructures are achieved using TMIn/TEGa under the same growth conditions.