THEORETICAL CONSIDERATIONS OF THERMALLY STIMULATED DISCHARGE TECHNIQUES IN AMORPHOUS-SEMICONDUCTORS

Thermally stimulated discharge of a previously polarized and electroded dielectric, can generate a current with several peaks. The locations of the peaks along the thermally stimulated discharge current spectrum are characteristics of the particular mechanisms for the decay. Systematic analysis of the current peaks will yield information such as dipole relaxation characteristics and activation energies for intrinsic conduction or trapping parameters of electronic charges in the dielectric. When multilayer dielectrics such as amorphous semiconductor photoreceptors are subjected to an electret formation cycle, the heterogeneity in their structures may cause several polarization effects. For example, discontinuities in the intrinsic conductivities and dielectric constant in amorphous selenium (a-Se)-based multilayer photoreceptors can lead to the accumulation of space charges at the interfaces of the individual layers whenever the device experiences an electric stress for a period of time which is of the order of its effective dielectric relaxation time. Charge trapping by states associated with the heterogeneities of the structure cause an electrical polarization which can have a significant impact on the xerographic performance of the photoreceptor. The purpose of the present series of papers is firstly to describe the principles of thermally stimulated discharge techniques, the associated theories and interpretation of the current spectrum and secondly, to discuss applications of these techniques to a-Se:Te/Se double layer photoreceptors. The principles of thermally stimulated discharge and relevant theories are discussed.