Optical studies of ZnS:Mn films grown by pulsed laser deposition

High-quality ZnS:Mn thin films have been deposited on (001)Si substrates at various temperatures using pulsed laser deposition. Their structural properties were characterized by x-ray diffraction. Optical studies by spectroscopic ellipsometry, optical transmittance, and photoluminescence measurements were systematically carried out on all film samples. In the analysis of the measured SE spectra, a modified double-layer Sellmeier model was adopted to represent the optical properties of the ZnS:Mn films. In this model, the films were assumed to consist of two layers-a bottom bulk ZnS:Mn layer and a surface layer composed of bulk ZnS:Mn as well as void. Good agreement was obtained between the measured spectra and the model calculations. Changes in the refractive indices of the ZnS:Mn films as a function of growth temperature were investigated. The PL and absorption measurements revealed that the orange-yellow emission band at similar to590 nm and the absorption edge at similar to370 nm upshifted to shorter wavelengths for films deposited at higher substrate temperatures. These results imply that the energy gap of the ZnS:Mn films increases with growth temperature. The observed changes of optical properties in these films are correlated to their structural qualities. (C) 2002 American Institute of Physics.