Anderson localization and Monte Carlo simulation of vertical transport in disordered finite superlattices

The effects on the carrier wave functions of introducing monolayer disorder at the heterojunction interfaces of an undoped superlattice are elucidated. In particular the rate and extent of the resulting localization is quantified by means of an entity C, which is the joint probability of finding two carriers in the same region of space. Evaluating the latter for all states in the miniband provides clear evidence for the existence of a mobility edge in finite two-dimensional structures. Using the entity C as the basis for a semiclassical evaluation of carrier transport, it is shown that the experimentally observed activated transport can be accounted for in terms of the excitation of carriers from the localized states at the bottom of the miniband into the more extended midband miniband states. Comparison of the theoretical results with the experimental results given [Chen et al., J. Cryst. Growth 159, 1066 (1996)], enables conclusions to be drawn concerning the mechanism of activated carrier transport in doped superlattice systems. (C) 1997 American Institute of Physics. [S0021-8979(97)08221-2].