Electronic structure and optical properties of CdSxSe1−x solid solution nanostructures from X-ray absorption near edge structure, X-ray excited optical luminescence, and density functional theory investigations

Abstract

The electronic structure and optical properties of a series of iso-electronic and iso-structural CdSxSe1−x solid solution nanostructures have been investigated using X-ray absorption near edge structure, extended X-ray absorption fine structure, and X-ray excited optical luminescence at various absorption edges of Cd, S, and Se. It is found that the system exhibits compositions, with variable local structure in-between that of CdS and CdSe accompanied by tunable optical band gap between that of CdS and CdSe. Theoretical calculation using density functional theory has been carried out to elucidate the observations. It is also found that luminescence induced by X-ray excitation shows new optical channels not observed previously with laser excitation. The implications of these observations are discussed.