Monte Carlo modeling of high-field transport in III-V heterostructures

Abstract

A Monte Carlo model of parallel high-field transport in III-V heterostructures is presented. Special features of the model are the following: only two-dimensional electron states are considered, the possible existence of secondary wells inside the barriers is accounted for, and nonparabolicity effect and quantization of satellite valleys are included. The wave functions and eigenenergies are calculated by self-consistent resolution of Poisson and Schrödinger equations. The effect of nonparabolicity on dispersion relations is determined at first order by a perturbation method. First, the simple case of an infinite GaAs square well is investigated as a test for the model, then more realistic heterostructures are considered. A study of a modulation-doped pseudomorphic AlxGa1−xAs/In0.15Ga0.85As structure shows that the electric field induces a significant repopulation of the doped AlGaAs layer. When x=0.32, this real-space transfer is strongly correlated with the intervalley transitions toward X valley states. For In0.52Al0.48As/In0.53Ga0.47As the situation is quite different and a good confinement in the InGaAs well is preserved even at high fields owing to the large band offset in the L valley. This study demonstrates a complicated influence of band structure on electron transport in heterostructures.