DIFFUSION OF PHOTOINJECTED CARRIERS IN NONEQUILIBRIUM POLAR SEMICONDUCTORS

Ambipolar diffusion of photoinjected carriers in nonequilibrium polar semiconductor plays, in conjunction with other effects, an important role in the relaxation processes in such hot carrier systems, providing a mechanism for a slowing down of the relaxation processes. Diffusion processes are governed by an ambipolar diffusion coefficient. In these far-from-equilibrium semiconductors such transport coefficient depends on the nonequilibrium macroscopic state of the sample, as it evolves in time. Resorting to an informational statistical thermodynamics, we derive an expression for this ambipolar diffusion coefficient accounting for its dependence on the time evolution of the dissipative processes that develop in the medium. The theoretical results are compared with experimental data obtaining a good agreement.