Einstein Relation For Nonlinear Charge Transport In Photoexcited Polar Semiconductors

We consider nonlinear charge transport of carriers in a photoexcited plasma in polar semiconductors. The diffusion and mobility kinetic coefficients in such conditions are obtained resorting to a nonequilibrium statistical thermodynamic approach. A generalized Einstein relation is derived for the nonequilibrium carriers (electrons and holes) for weak and intermediate electric field strengths. We discuss the effect of the irreversible evolution of the system and of the non-Ohmic behavior on such generalized Einstein relation. © 1994.928649653Nernst, (1888) Z. Phys. Chem., 2, p. 613Townsend, The Diffusion of Ions into Gases (1899) Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 193, p. 129Einstein, (1965) Investigations on the Theory of the Brownian Motion, , R. Furth, Dover, New York, in reprints inMason, McDaniel, (1988) Transport Properties of Ions in Gases, , Wiley, New YorkAlgarte, Vasconcellos, Luzzi, Kinetics of Hot Elementary Excitations in Photoexcited Polar Semiconductors (1992) physica status solidi (b), 173, p. 487Algarte, Vasconcellos, Luzzi, (1993) Solid State Commun., 87, p. 229Vasconcellos, Algarte, Luzzi, (1993) Phys. Rev., 48 B, p. 10873Freire, (1988) Ph.D. thesis, , UNICAMP, Campinas, São Paulo, Brazil, Ultrafast transient transport in plasma in semiconductorsFreire, Vasconcellos, Luzzi, (1989) Phys. Rev., 39 B, p. 13264Ziman, (1960) Electrons and Phonons: The Theory of Transport Phenomena in Solids, , E.g., Oxford Univ. Press, LondonConwell, (1967) Solid State Physics Series, pp. 1-281. , E.g., F. Seitz, D. Turnbull, E. Ehrenreich, Academic, New York, Suppl.