Amorphous Built-in-Field Effect Photoreceptors

Thin-film photodiodes with the graded-composition structures of amorphous Se–As–Te have been developed. The physical mechanism of the buit-in-field effect in these highly resistive photodiodes has been clarified. In order to realize complicated composition distributions, multi-layer evaporation technology has also been developed. The physical properties of multi-layered films and those of the uniform amorphous film have been compared, and it has been shown that a multi-layered film of 1 nm periodicity can be regarded as an almost uniform amorphous material. Built-in-field effect photoreceptors can be utilized not only for TV pickup tubes but also for highly sensitive xerographic plate and other solid-state sensors.