The photoluminescence and optical constant of ZnSe/SiO 2 thin films prepared by sol–gel process

Abstract

In this paper, ZnSe/SiO 2 thin films were prepared by sol–gel process. X-ray diffraction results indicate that the phase structure of ZnSe particles embedded in SiO 2 thin films is sphalerite (cubic ZnS). The dependence of ellipsometric angle ψ on wavelength λ of ZnSe/SiO 2 thin films was investigated by spectroscopic ellipsometers. The optical constant, thickness, porosity and the concentration of ZnSe/SiO 2 composite thin films were fitted according to Maxwell–Garnett effective medium theory. The thickness of ZnSe/SiO 2 thin films was also measured by surface profile. The photoluminescence properties of ZnSe/SiO 2 thin films were investigated by fluorescence spectrometer. The photoluminescence results reveal that the emission peak at 487 nm (2.5 eV) excited by 395 nm corresponds to the band-to-band emission of sphalerite ZnSe crystal (2.58 eV). Strong free exciton emission and other emission peaks corresponding to ZnSe lattice defects are also observed.