Structural asymmetry induced size quantized nonmonotonous electron mobility in GaAs/AlxGa1−xAs double quantum well structure

Abstract

We show that nonmonotonic enhancement of low temperature electron mobility μ can be achieved in GaAs/AlxGa1−xAs barrier delta doped double quantum well structure under double subband occupancy. We vary the well widths asymmetrically by shifting the position of the central barrier and analyze its effect on the multisubband electron mobility taking different doping profiles. It is gratifying to show that when there is delta doping in one of the side barriers, a hump in μ is achieved as a function of the well width which enhances with increase in the width of the central barrier. On the other hand, when both the side barriers are symmetrically doped, a dip in μ is exhibitted which increases with increase in the doping concentration. In the former case, the mobility is mostly contributed from the higher subband limited by the ionized impurity scattering. Whereas, in the later case, the wavy nature of mobility is due to the drastic variation of subband mobilities through the interface roughness scattering.