Theory of electronic transport in two-dimensional Ga0.85In0.15As/Al0.15Ga0.85As pseudomorphic structures

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Abstract
We present calculations of the electron drift velocity and valley populations as a function of applied electric field in two different Ga0.85In0.15As/Al0.15Ga0.85 As heterostructure systems which show two‐dimensional size quantization effects. Electronic transport in both a pseudomorphic, double heterostructure system formed by use of three separate semiconductor layers is examined and compared to that of a simpler two‐layer, single heterostructure. The calculations are made based on an ensemble Monte Carlo simulation which includes the full physics of the two‐dimensional system. The double heterostructure consists of a Ga0.85In0.15 As quantum well bordered on one side by a highly doped (1×1018 1/cm3 ) Al0.15Ga0.85 As layer and on the other by a nearly intrinsic GaAs layer consistent with the design of most pseudomorphic high electron mobility transistors. In order to assess the effect of the electronic confinement within the quantum well on the resulting carrier velocities, the results are compared to calculations of the electron drift velocity in a single heterostructure. The single‐heterostructure system consists of two separate layers of doped Al0.15Ga0.85 As and nearly intrinsic Ga0.85In0.15 As. It is found that the electron drift velocity and mobility is much larger within the double heterostructure than within the single heterostructure over a wide range of applied electric field strengths. The presence of the surrounding GaAs layer in the double heterostructure acts to confine the electrons within the two‐dimensional system resulting in a significant increase in the average steady‐state electron drift velocity.