Amorphous selenium is often used as the basic photoreceptor material in xerography in the form of a layer on an aluminum substrate. It is found that the dark decay rate of charge on the selenium surface can be reduced by the presence of a thin aluminum oxide film between the selenium and the substrate metal. In this study, different methods were explored for forming this film, including direct thermal oxidation and various glow-discharge methods. It was found that with thermal oxidation and low voltage glow discharge, the film thicknesses were limited to about 200 Å (1 Å = 10−10 m). However, with dc reactive sputtering, aluminum oxide films with thicknesses of more than 2000 Å could be prepared. Evaluation of the films, with the selenium layer present, indicated that the low voltage glow-discharge and direct thermal oxidation methods gave the best results xerographically.
The Development of Spark Discharges in Hydrogen