GRAIN-BOUNDARY EFFECT IN POLYCRYSTALLINE ZNTE FILMS

Electrical and optical properties of ZnTe films, deposited at different substrate temperatures (300-630 K) by hot-wall vacuum evaporation, were studied. The experimental data were analysed in the light of the grain boundary trapping model in polycrystalline films. The crystallites were found to be partially depleted of carriers. The barrier height along with the carrier concentration in the films were determined from the optical reflectance measurements. The effect of deposition temperature on the film properties has been critically discussed. The density of trap states in the intercrystalline region of the films was found to decrease with increasing deposition temperature. The built-in electric field in the crystallites was evaluated for different sizes of the crystallites.