Rectification and the Anomalous Photovoltaic Effect in ZnS Crystals

Abstract

The current‐voltage characteristics of insulating ZnS crystals were measured for various monochromatic excitations. A rectification dependent on crystallographic polarity was observed. The spectral dependence of the rectification ratio is similar to the spectral dependence of the positive anomalous photovoltage. The rectification is attributed to the action of the same internal fields which were investigated by electro‐absorption measurements and which cause the generation of the anomalous photovoltaic effect. The electrical characteristics were correlated with other photoelectric properties of ZnS crystals and with the gross structure of the crystals, i.e., with the structure of the various regions of which a given crystal is composed. The origins of the internal fields and the mechanism of the negative photovoltage generation are also discussed.