Field-enhanced mobility in the multiple-trapping regime

Charge transport in disordered inorganic semiconductors is governed by the multiple trapping (MT) of carriers from delocalized states in the conduction band into localized traps in the band tail. Although it is well known that carrier mobility in these materials strongly depends on electric field, a consistent description of this effect in the MT regime is still missing. We analyze experimental data obtained in a series of disordered inorganic semiconductors and show that the combined effects of temperature and of the electric field on the carrier mobility can be described by a single parameter, the field-dependent effective temperature. This conclusion is supported by the theoretical analysis of the MT transport, which takes into account the field-assisted release of carriers from the traps into the conduction band.