Mechanisms of charge carriers nonequilibrium in transport processes in bipolar semiconductors

Abstract

The interplay between physical origins of the nonequilibrium and their influence on the linear steady state transport processes in bipolar semiconductors are under investigation. Particular attention is paid to the influence of the energy nonequilibrium on the generation-recombination processes under various conditions. It is shown that in the case of the same (even if coordinate-dependant) temperature of the charge carriers and the phonons the volume recombination rate of the charge carriers in the steady state is completely determined by the splitting of the quasi-Fermi levels.Particular emphasis has been placed on the manifestation of the energy nonequilibrium in the presence of hot charge carriers in a semiconductor. It is shown that in this case the generation-recombination balance shifts, being completely equivalent to the appearance of an additional external generation of electron-hole pairs. The two-temperature model (with electron temperature being different from the single temperature of holes and phonons) of the Dember photovoltaic effect is used to illustrate that the electromotive force (emf) may differ significantly from its corresponding values with no hot electrons. This additional contribution to the emf does not depend neither on the Seebeck coefficient nor on the temperature gradient and the electron-hole pair generation rate. This contribution to the emf is exclusively determined by the magnitude of the electron heating.