Pressure Dependence of Optical Transitions in In-rich Group III-Nitride Alloys

Abstract

ABSTRACTThe hydrostatic pressure dependence of the optical transitions in InN, In-rich In1-xGaxN (0 < x < 0.5) and In1-xAlxN (x = 0.25) alloys is studied using diamond anvil cells. The absorption edges and the photoluminescence peaks shift to higher energy with pressure. The pressure coefficient of InN is determined to be 3.0±0.1 meV/kbar. Together with previous experimental results, our data suggest that the pressure coefficients of group-III nitride alloys have only a weak dependence on the alloy composition. Photoluminescence gives much smaller pressure coefficients, which is attributed to emission involving highly localized states. This indicates that photoluminescence might not be an accurate method to study the pressure dependence of the fundamental bandgaps of group III-nitrides.