Bandgap Engineering in Wurtzite GaAs Nanowires by Hydrostatic Pressure**Supported by the National Natural Science Foundation of China under Grant No 11474275.

Abstract

Band structure of wurtzite (WZ) GaAs nanowires (NWs) is investigated by using photoluminescence measurements under hydrostatic pressure at 6 K. We demonstrate that WZ GaAs NWs have a direct bandgap transition with an emission energy of 1.53 eV, corresponding to the optical transition between conduction band Γ7C and valence band Γ9V in WZ GaAs. The direct-to-pseudodirect bandgap transition can be observed by applying a pressure approximately above 2.5 GPa.