CdO/ZnO multiple quantum wells as components for next generation solar cells

Abstract

We report on time-resolved and steady state photoluminescence (PL) studies of strained ZnxCd1-xO/ZnO MQW structures grown on c-plane and r-plane sapphire substrates by Metaloranic Vapor Phase Epitaxy. The high crystalline quality of all MQW structures was confirmed by X-ray diffraction measurements. No emission related to ZnO barriers could be resolved in PL spectra implying effective carrier confinement in the quantum wells. The estimated built-in electric field from optical transition is of the order of ~ 1.75 MV/cm. The observed spectral and carrier lifetime variations are discussed in terms of quantum confinement and internal electric field modulation induced by strain.