The photoluminescence and optical constant of ZnSe/SiO2 thin films prepared by sol-gel process

In this paper, ZnSe/SiO2 thin films were prepared by sol-gel process. X-ray diffraction results indicate that the phase structure of ZnSe particles embedded in SiO2 thin films is sphalerite (cubic ZnS). The dependence of ellipsometric angle psi on wavelength X of ZnSe/SiO2 thin films was investigated by spectroscopic ellipsometers. The optical constant, thickness, porosity and the concentration of ZnSe/SiO2 composite thin films were fitted according to Maxwell-Garnett effective medium theory. The thickness of ZnSe/SiO2 thin films was also measured by surface profile. The photoluminescence properties of ZnSe/SiO2 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. (C) 2006 Elsevier Ltd. All rights reserved.