Structural asymmetry induced enhancement of electron mobility in coupled double quantum well structures

Abstract

We study the enhancement of electron mobility through structural asymmetry of a delta doped GaAs/Al x Ga 1%x As coupled quantum well structure. We obtain the subband energy levels and wave functions through selfconsistent solution of the Schrodinger equation and the Poisson's equation. We calculate the low temperature electron mobility by considering screened scattering potentials due to ionized impurities, interface roughness and alloy disorder by adopting random phase approximation. We show that the mobility increases with increase in the asymmetry of the doping concentrations. The change in mobility due to interchange of doping concentrations of the barriers is because of asymmetry of the interface roughness scattering potential. The barrier dependent enhancement in mobility is controlled by the variation of the subband Fermi wave vector through splitting in the subband energy levels. We show that the range of well width, up to which the interface roughness scattering dominates, depends on the doping concentration through intersubband effects.