Photosensor having an amorphous silicon photoabsorption layer

Abstract

A photosensor comprises an insulator layer, a first electrode on the insulator layer for collecting first type carriers formed upon incidence of optical radiation, the first electrode being segmented into a plurality of pixel electrodes separated from each other by a gap, a first silicon carbide layer provided on the insulator layer to cover the plurality of pixel electrodes including the gap separating adjacent pixel electrodes, an optical absorption layer of amorphous silicon provided on the silicon carbide layer continuously such that the amorphous silicon layer extends over the plurality of pixel electrodes and the gap between adjacent pixel electrodes, the optical absorption layer producing the first type carriers and second type carriers having opposing polarity to the first type carriers upon incidence of the optical radiation, a second silicon carbide layer provided on the amorphous silicon layer for protecting the optical absorption layer from chemical reaction, and a second electrode of a transparent material provided on the silicon carbide layer for collecting the second type carriers produced in the optical absorption layer, wherein the first silicon carbide layer is doped to have a conductivity that enables formation of an electric field equal to or larger than about 4 volts/.mu.m in magnitude in the amorphous silicon layer and such that the conductivity is equal to or smaller than the conductivity of the amorphous silicon layer.