MONTE-CARLO STUDY OF DIFFUSION PHENOMENA IN III-V MODULATION-DOPED HETEROSTRUCTURES

This paper presents a Monte Carlo study of diffusion coefficients in t wo-dimensional electron gas (TDEG) in III-V heterostructures. The mode l accounts for the quantization of all valleys and for non-parabolicit y. The diffusion coefficients are determined by the spreading of a nar row pulse of carriers drifting along the interface. Two kinds of heter ostructures have been considered: AlGaAs/lnGaAs/AlGaAs and the AllnAs/ lnGaAs/AllnAs lattice matched on InP. The diffusion coefficient-field characteristics at 77 K temperature have been extensively studied. Lar ge deviations from the Einstein relation have been observed, even at l ow-fields. The longitudinal diffusion coefficient is shown to be stron gly field dependent and may reach high values for fields around 1 kV c m(-1). Its evolution is explained by the behaviour of scattering rates , especially for impurity and phonon scattering.