Modeling of temperature and field dependent effective hole mobility at high fields in amorphous selenium

An analytical model is presented to show the mechanisms of the electric field and temperature dependent effective drift mobility of holes in amorphous selenium (a-Se) considering the density of states distribution, thermally activated tunneling for the field enhancement release rate, and carrier heating. In addition, the model for the field-dependent microscopic mobility considering carrier heating is also proposed. The results of this model are fitted with the published experimental results on effective mobility with wide variations of applied electric fields and temperatures. The analyses of these fittings revealed that the microscopic mobility in a-Se decreases whereas the effective drift mobility increases with increasing the field and temperature.