SeBiI alloy: A high sensitivity visible—near IR photoconductor

Abstract

The development and characterization of an amorphous SeBiI alloy system whose electrophotographic sensitivity is substantially greater than either selenium or arsenic triselenide at all visible wavelengths and whose sensitivity extends beyond 800 nm are described. Amorphous films were prepared by flash evaporation in vacuum of thermally blended alloys. A composition matrix of bismuth and iodine in selenium was surveyed to identify the optimum alloy. Alloys containing approximately equal amounts of bismuth and iodine were found to be more structurally stable and have more desirable electrophotographic properties than either alloys varying from these compositions or the iodine-free selenium-bismuth binary system. The optimum alloy contained about 3 at% bismuth, 3 at% iodine and 94 at% selenium. The alloy system would appear to have utility wherever panchromaticity or near infrared sensitivity is required and thin photogeneration layers can be tolerated. Potential applications lie in devices with multilayer configurations, in image orthicons and laser coupled devices.