Photovoltages in Silicon and Germanium Layers

Abstract

Photovoltages up to a few hundred volts at room temperature and up to a few thousand at liquid nitrogen temperatures were observed under strong illumination in silicon and germanium layers with a distance of about 1 cm between electrodes. Only samples with a thickness gradient of evaporated material exhibited these photovoltages. In both the Ge and the Si layers the photovoltage showed an almost linear relationship with illuminating intensity. Both the magnitude and sign of the voltage depended on which side of the film was irradiated, the wave length of incident light, and the temperature. The dark resistance of these layers varied between 1011 and 1014 ohms. A theoretical interpretation of the origin of these voltages is given.