High-Voltage Photovoltaic Effect in Evaporated CdTe Films

Abstract

The properties of CdTe films vacuum-evaporated at an oblique angle of incidence onto a substrate of glass, which are known to exhibit unusually high photovoltages, are experimentally studied. (1) The angular distribution of the intensity of light scattered by the film is asymmetric. (2) The (111) planes of the crystallites do not lie parallel to the substrate surface, as they do in the case of normal incidence. The incline of the (111) planes is determined in the main by the angle of incidence of vapor θ. (3) The photovoltage V exhibits a peculiar dependence on θ. It changes its sign at a certain value of θ, which in turn is determined by the substrate temperature. A model is proposed for the structure of the film, which will explain the experimental results.