Field-dependent tunneling and population inversion in multiband semiconductor superlattices

The quasiclassical description of high-field effects in one-band superlattices is extended to multiband systems. Field-dependent tunneling is taken into account within a density-matrix approach. Analytical results are derived for the field dependence of the carrier redistribution in two- and three-band semiconductor superlattices. Some implications for the design of unipolar mid-infrared lasers are discussed.