Transient space-charge-limited currents in photoconductor-dielectric structure: A field-dependent mobility case

A general formulation of the photoconducting behavior of a composite photoconductor having three different field-dependent mobilities, viz., field independent, power-law field dependent, and exponential-law field dependent, under all possible time (within and beyond the transit time of the fastest carrier), physical (space-charge limited, space-charge perturbed, and emission limited), and circuit (open and closed) modes is developed and solved. Due to the complex nature of the problem extensive numerical calculations are necessary for the field-dependent mobility cases. The time evolution of five basic photoconducting variables, viz., the electric field, the current, the voltage drop, the charge inside, and the charge density at the surface of the photoconductor are calculated. The novel feature in this study is the calculation of the above five entities for a composite photoreceptor having field-dependent mobility, in the current mode, beyond the transit time.