Merlin E. Scharfe

Bulk Space Charge and Transient Photoconductivity in Amorphous Selenium

The drift of a small photoinjected sheet of free carriers can be used as a probe of the space charge and internal field distributions in the bulk of amorphous selenium films. We have found that unneutralized space charge can exist for long periods of time and can significantly affect the measurement of both drift mobility and deep trapping lifetimes. By deliberately creating bulk space charge, we can also examine some of the fatigue effects that arise when a selenium photoreceptor is not allowed to relax between large variations in applied field and exposure.

Transition from Emission‐Limited to Space‐Charge‐Limited Photoconductivity

A transition from an initial emission‐limited current to a steady‐state space‐charge‐limited current has been observed in evaporated films of amorphous selenium. A simple model of this transition has been developed which can be used to illustrate the trapping dynamics and estimate the free carrier range.

Field dependent drift mobilities in amorphous semiconductors

Abstract The experimentally measured electric field dependence of the hole drift mobilities in amorphous Se at 180°K, amorphous As2Se3 and PVK at room temperature are presented and compared with a recently published formalism. The theoretical field dependence of the drift mobility is found to be inconsistent with the measurement.