Application of thermally stimulated discharge techniques to a-Se: Te/Se double-layer photoreceptors

Abstract

Interface traps in a-Se:Te/Se double-layer xerographic photoreceptors were studied using thermally stimulated discharge (TSD) techniques. Two peaks are found in the TSD current curve which are believed to be due to two distinctly different types of space charge polarization. The well-defined low-temperature peak is centred at approximately −8 °C and it is due to the difference in the dielectric constants and electrical conductivities of a-Se:Te and a-Se layers. It is argued that on the application of an electric field with positive polarity applied to the a-Se:Te layer, the Maxwell-Wagner effect causes the build up of a positive (holes) space charge layer at the interface of the two layers. The observed TSD current peak seems to be dominated by the neutralization currents in the a-Se:Te layer. The broad high-temperature peak occurs between 30 and 50 °C in the thermograms and it is believed to be due to release of holes from the deep traps at the interface between the two layers. The density of these traps is estimated to be ∼1010 cm−3. The activation energy relaxation corresponds to the effective energy for the detrapping of holes from the interface states and is calculated to be ∼ 0.54 eV.