OPTICAL CHARACTERISTICS OF THIN ZNSE FILMS OF DIFFERENT THICKNESSES

Polycrystalline ZnSe films of thicknesses 54-785 nm deposited on glass substrates by thermal evaporation were investigated. X-ray diffractio n analysis was carried out on as-deposited and annealed films to deter mine their structure. The ZnSe films were polycrystalline of cubic str ucture with preferred [111] orientation. Transmission and reflection a t normal incidence were performed on ZnSe films in the wavelength rang e 350-2500 nm to determine the optical constants and optical energy ga p. The optical gaps of ZnSe films show remarkable dependence on the fi lm thickness. Analysis of the absorption data revealed the existence o f two transition processes (with energy gaps at 2.7 and 2.22 eV for th e bulk ZnSe).