Luminescence properties of a ZnO–In2O3 composite

Abstract

ZnO–In2O3 composite was prepared by thermal annealing of ZnIn2S4 crystals. Energy dispersive X-ray analysis demonstrated that annealing results in the formation of a composite consisting of ZnO and In2O3 phases with the ratio 1:1 as well as of a small amount of the initial ZnIn2S4 phase, which concentration depends on the duration of annealing. The composite exhibits bright luminescence with different colors coming from different constituents, the spectral distribution being dependent upon the wavelength of excitation. The photoluminescence spectrum is predominated by ultraviolet emission from the ZnO crystallites under the excitation by the 351 nm line of an Ar+ laser, while a blue-green photoluminescence band related to the In2O3 crystallites emerges under the excitation by the 334 nm line. The sample reveals a bright red emission form the ZnIn2S4 phase when it is excited by the blue-green light. The electronic transitions responsible for the observed luminescence lines are discussed.