ABSTRACT
I. INTRODUCTION The fundamental image-forming process in xerography is the creation of an electrostatic latent image on the surface of a photoconducting insulator. To create the latent image, the photoreceptor is charged by a corona discharge and then exposed to an imagewise pattern of radiation. The absorption of radiation creates bound electron-hole pairs. Under the influence of the field, the pairs separate and migrate to the appropriate surfaces. Thus the corona-deposited surface charge is dissipated in the exposed regions and a latent image is created that corresponds to the image that is to be reproduced. There are several photoreceptor require ments for xerography: (1) the rate of thermal generation of free carriers must be extremely low; (2) the photoreceptor must have high sensitivity throughout the appropriate region of the spectrum; (3) the charge transport processes must occur in the absence of deep trapping over an extended range of fields; and (4) the electronic properties must be stable to highly oxidizing corona atmospheres under high field and exposure conditions. A final requirement is that the photoreceptor have good mechanical properties and high abrasion resistance.
