Investigation of n-CdSp-CdTe Thin Film Heterojunctions

Abstract

Current—voltage, current—capacitance, photosensitivity, temperature, and spectral characteristics of SnO2n-CdSp-CdTeMe thin film structures have been investigated. The experimental results are explained by electron processes taking place in n-CdSp-CdTe heterojunctions. An n-CdSp-CdTe energy band diagram is suggested taking into account both surface charge and formation of an electrical dipole by interface states. An analysis of the experimental results on the basis of this model leads to a multi-step recombination—tunnelling mechanism. As may be seen from the n-CdSp-CdTe energy band diagram, both tunnelling and recombination develop in the narrow band gap material (CdTe). The number of tunnelling steps and the height of the barrier for each step have been determined for forward and reverse currents. Thin film photodiode arrays have been performed and investigated, which may serve as a multi-channel electrical input in optoelectronic systems.