Comparison between semiclassical and full quantum transport analysis of THz quantum cascade lasers

We implement and compare two theoretical models for stationary electron transport in quantum cascade lasers and Stark ladders. The first one, the nonequilibrium Green's function method is a very general scheme to include coherent quantum mechanics and incoherent scattering with phonons and device imperfections self-consistently. However, it is numerically very demanding and cannot be used for systematic device parameter scans. For this reason, we also implement the approximate, numerically efficient ensemble Monte Carlo method and assess its applicability on the above mentioned transport problems. We identify a transport regime in which results of both methods quantitatively agree. In this regime, the ensemble Monte Carlo method is well suited to propose design improvements. (C) 2009 Elsevier B.V. All rights reserved.