MONTE-CARLO MODELING OF HIGH-FIELD TRANSPORT IN III-V HETEROSTRUCTURES

A Monte Carlo model of parallel high-field transport in III-V heterost ructures is presented. Special features of the model are the following : only two-dimensional electron states are considered, the possible ex istence of secondary wells inside the barriers is accounted for, and n onparabolicity effect and quantization of satellite valleys are includ ed. The wave functions and eigenenergies are calculated by self-consis tent resolution of Poisson and Schrodinger equations. The effect of no nparabolicity on dispersion relations is determined at first order by a perturbation method. First, the simple case of an infinite GaAs squa re well is investigated as a test for the model, then more realistic h eterostructures are considered. A study of a modulation-doped pseudomo rphic AlxGa1-xAs/In0.15Ga0.85As structure shows that the electric fiel d induces a significant repopulation of the doped AlGaAs layer. When x = 0.32, this real-space transfer is strongly correlated with the inte rvalley transitions toward X valley states. For In0.52Al0.48As/In0.53G a0.47As 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 influenc e of band structure on electron transport in heterostructures.