There are two mechanisms of conduction in a semiconductor: diffusion and drift. Diffusion current, on one hand, is clearly affected by changes in bias because the number of majority carriers that are able to diffuse across the junction varies exponentially according to the Maxwell-Boltzmann...
The magnitude of a drift current density is given by J = qnv, where q is the carrier charge, n is the carrier density per unit volume, and v is the carrier drift velocity. q is a physical constant and n is independent of bias. But when an external electric field is applied, the minority charge...