Physical properties of ZnSe thin films deposited on glass and silicon substrates

Abstract

ZnSe thin films were deposited onto Corning glass and silicon substrates using thermal evaporation. The samples were prepared at different substrate temperatures. The thin films’ surface chemical composition was determined through Auger electron spectroscopy (AES). AES signals corresponding to Zn and Se were only detected in AES spectra. The samples’ crystallographic structure was studied through X-ray diffraction. The material crystallised in the cubic structure with preferential orientation (111). Optical properties of the ZnSe films were studied over two energy ranges via electron energy loss spectroscopy (10–90eV) and spectral transmittance measurements (0.4–4eV). In both cases, the spectral variation of the refractive index and the absorption coefficient were determined by fitting the experimental results with well-established theoretical models. Experimental values for the material’s gap were also found, and photoconductivity (PC) measurements were carried out. Transitions between bands, usually labelled ΓV8 → ΓC6 and ΓV7 → ΓC6, were found in the optical and PC responses. A wide spectral photoconductive response between 300 and 850nm was found in the ZnSe/Si samples prepared at 250°C substrate temperature.