Effect of external electric field on multisubband electron mobility in n-V-shaped double quantum well HEMT structure

Abstract

In this work, we present theoretically the effect of external electric field Fe on low temperature multisubband electron mobility μ in V-shaped double quantum well (V-DQW) HEMT structure. We consider the impact of ionised impurity and alloy disorder scatterings for the calculation of μ. We show that, in the proposed structure, when Fe, is absent, there are two subbands occupied below the Fermi levels. However, as Fe increases, there is an alteration of the potential profile, which changes the energy levels and wave function distributions leading to variation of occupation of subband states, i.e. from double to single. During double subband occupancy, initially, μ enhances with Fe, attains a peak value and then decreases. Whereas, for Fe where the transition from double to single subband occupancy occurs, there is a sudden rise in μ due to the cease of inter-subband interaction. It is interesting to note that different structure parameters, e.g. well widths Ww, central barrier width BC, doping concentrations ND, alloy concentrations xv at the well edges of the V-DQW have a fascinating impact on μ. We show that increasing Ww, and BC and decreasing ND, and xv enhances μ.