Monte Carlo study of diffusion phenomena in III - V modulation doped heterostructures

This paper presents a Monte Carlo study of diffusion coefficients in two-dimensional electron gas (TDEG) in III - V heterostructures. The model accounts for the quantization of all valleys and for non-parabolicity. The diffusion coefficients are determined by the spreading of a narrow pulse of carriers drifting along the interface. Two kinds of heterostructures have been considered: AlGaAs/InGaAs/AlGaAs and the AlInAs/InGaAs/AlInAs lattice matched on InP. The diffusion coefficient - field characteristics at 77 K temperature have been extensively studied. Large deviations from the Einstein relation have been observed, even at low-fields. The longitudinal diffusion coefficient is shown to be strongly field dependent and may reach high values for fields around . Its evolution is explained by the behaviour of scattering rates, especially for impurity and phonon scattering.