Effect of carbon tetrabromide on the morphology of GaAs nanowires

摘要

Carbon is a commonly used p-type dopant in planar III-V semiconductors, however its use in nanowire (NW) growth has been much less reported. In this work we show that the morphology of gold assisted GaAs NWs can be strongly modified by the presence of CBr_4 vapor during growth by metalorganic vapor phase epitaxy. GaAs NWs were grown under conditions which result in strong tapering and lateral growth at low growth temperatures by the use of triethylgallium (TEGa) instead of the more usual precursor, trimethylgallium (TMGa). Under these conditions, NWs grown in the presence of CBr_4 exhibit higher axial and lower radial growth rates, and negligible tapering compared with NWs grown in the absence of CBr_4 under the same conditions. We attribute this primarily to the suppression of the 2d growth rate by CBr_4, which enhances the axial growth rate of the nanowires. NWs grown with CBr_4 show stacking-fault-free zincblende structure, while the NWs grown without CBr_4 show a high density of stacking faults. This work underlines the striking effects which precursor chemistry can have on nanowire morphology.