Xerographic properties of a Se:Te photoconductors

In this paper due to their desirable spectral response, amorphous Se:Te alloys are widely used as commercial xerographic photoreceptor materials. It is shown that the dark decay of the electrostatic surface potential on a corona-charged a-Se:Te alloy photoreceptor occurs via electric field-enhanced xerographic depletion discharge (FEXDD) in which Polle-Frenkel-assisted thermal emission of holes from deep mobility-gap states and their subsequent sweep out generates a negative bulk space charge. A theoretical expression is derived for the dependence of the xerographic depletion time td and the time required for the surface potential to decay to half its value t1/2 on the initial charging voltage V0. Experimental data show good agreement with the theory and enable the Poole-Frenkel coefficient for a-Se:Te to be evaluated. Furthermore, it is shown that at the highest charging voltages, t1/2 actually decreases with V0, which is directly attributable to the FEXDD process