STRUCTURE-DEPENDENT WEAK-LOCALIZATION MODEL FOR A SUPERLATTICE

A tight-binding theory of weak localization in the parallel and vertical conductivity of a semiconductor superlattice is presented. We take into account both the electron wave-function modulation in a superlattice and a spatial distribution of impurities in the potential barriers. These features allow us to perform realistic small-collisional-broadening calculations as quantum corrections to the Boltzmann transport. We obtain the anisotropic-elastic-scattering time, even in the case of pointlike scatterers. The anisotropy of our model differs from that considered by Bhatt, Wolfle, and Ramakrishnan. In particular, the diffusion propagator in the z direction depends on an effective diffusion constant that consists of a coherent band part and an incoherent hoppinglike part.