Dark discharge in hydrogenated amorphous silicon photoreceptors

Abstract

We have studied the electric field, thickness, and temperature dependencies of dark discharge in corona-charged glow-discharge amorphous silicon (a-Si:H) films. Dark discharge is a basic property for image devices such as photoreceptors. The dark-discharge rate ‖dV/dt‖ is found to be proportional to the square root of the electric field E as in the form log‖dV/dt‖∝√E, and increases nearly proportionally to the thickness of the a-Si:H film, indicating a bulk emission of charges from barriers lowered by electric fields like the Poole–Frenkel emission. It was also found that the contribution of electron injection from the substrate increases significantly in the dark discharge for small film thicknesses. The temperature dependence of dark discharge revealed the barrier height to be approximately 0.9 eV. A discharge mechanism was considered on the basis of these results, and was compared to that of other conventional materials for photoreceptors such as a-Se and a-As2Se3.