Electrical properties of epitaxial heterostructures on a zinc sulfide base

Abstract

An investigation is performed on the volt-ampere, volt-faraday, and photoelectrical characteristics of the epitaxial heterostructures n·ZnS-p-Ge, n-ZnS-p-GaAs, and n-ZnS-n-Si obtained by the method of vacuum evaporation in a quasiclosed volume. The heterotype structures are rectifying, and the current passage therein is described by the theories of space-charge-limited current. The quantity of surface states N_s.s=1.2·10¹²cm⁻² on the interface of n-ZnS-p-GaAs is computed, this being less than the theoretical value by almost two orders of magnitude. The heterostructures n-ZnS-n-Si were of two kinds. The volt-ampere characteristics of the structure of type I are rectifying with a rectification factor of 10⁴ at the 1 V level. The direct current had an exponential dependence and depended weakly on the temperature. The heterostructures had photosensitivity. Their no-load voltage was up to 0.2 V. The structures of type II had volt-ampere characteristics with “double saturation.” Starting from the model of two series-connected Schottky diodes, the heights of the barriers were computed for such heterostructures: Eg_ZnS=0.8–0.91 eV and E_Si=0.66–0.77 eV.