Currents under high driving forces

The current density vs. driving force relation is discussed for the hopping of localized charges between two neighboring sites under high driving force and high charge carrier concentration. First the bulk situation is treated, then the situation at the interface between two phases. To demonstrate the significance of these equations numerical simulations are presented for two cases of thin samples on which high driving forces are imposed. The results are compared with those obtained assuming a linear relation between the current density and the driving force.