Optoelectronic properties and electronic structure of YCuOSe

Abstract

YCuOSe was prepared by solid-state reaction, and its wide gap semiconducting properties were examined. The single phase of YCuOSe was obtained in a limited temperature range around 750°C and decomposed into Y2O2Se and Cu2Se at higher temperatures. The obtained YCuOSe sample showed a p-type semiconducting behavior with the electrical conductivity of 1.4×10−1Scm−1 at room temperature. The band gap of YCuOSe was estimated to be 2.58eV, which is much smaller than that of LaCuOSe (2.82eV). The electronic structure of YCuOSe was investigated by ultraviolet photoemission spectroscopy and energy band calculations to understand the differences in the electronic structures between LnCuOSe (Ln=La,Y). It was found that the Cu–Cu distance rather than the Cu–Se distance influences the electronic structures, and the smaller band gap of YCuOSe is attributed to the downshift of the Cu 4s energy level due to the smaller Cu–Cu distance and the consequent larger Cu–Cu interaction in YCuOSe.