Photoconductive registration element - comprising carrier with amorphous layer with first silicon and germanium contg. zone and second photoconductive silicon contg. zone

摘要

Photoconductive registration element comprises (A) a carrier and (B) an amorphous layer consisting of successive layers (from the carrier side) comprising (1) an amorphous layer of Si atom and Ge atom contg. material and (II) a second layer of amorphous Si atom contg. material which exhibits photoconductivity. Layers (I) and/or (II) may also contain H or halogen atoms. A second amorphous layer (I) may be provided on layer (B) and comprising Si atoms and C atoms opt. together with H or halogen atoms. The Ge atoms in layer (B1) may be unevenly distributed in the direction of the thickness of the layer and layer (B1) may also contain a substance to control the conductivity properties, e.g. a Gp.III metal such as B, Al, Ga, In or Tl, a p-type dopant, a Gp.V metal such as P, As, Sb or Bi; or an n-type dopant. The amorphous layer (B) may contain regions (P) and (N) contg. p-type and n-type dopants respectively, the regions (P) and (N) pref. being in contact with each other. Amorphous layer (B) may also contain O atoms which are unevenly distributed in the direction of the thickness of the layer. Pref. the ratio between the depths of the layers B1 and B2 is B1/B2 is less than or equal to 1. Materials have good sensitivity to electromagnetic radiation over a wide range of wavelengths, high signal/noise ratio (photocurrent Ip/dark current Id) and rapid response to light, and are made with non-hazardous materials. The prods. have properties suitable for document reading equipment, with the required electrical, optical and photoconductive properties, dark resistance, light sensitivity and response, and presenting no health hazards in the office environment.