Electric field induced enhancement of multisubband electron mobility in strained GaAs/InGaAs coupled quantum well structures

We analyze the enhancement of multisubband electron mobility due to an external electric field in a pseudomorphic GaAs/InxGa1−xAs coupled double quantum well structure. An electric field, applied perpendicularly to the interface plane, changes the potential energy profile of the structure. This change alters the energy level, wave function as well as the occupation of a subband. By varying the field, the system can be transformed from double subband occupancy to single subband occupancy resulting in an enhancement of the mobility due to the suppression of the intersubband effects. We consider scatterings due to the ionized impurities, interface roughness and alloy disorder and study the variations in the intrasubband and intersubband scattering matrix elements as a function of the electric field. The novelty of our work is the analysis of the effect of structure parameters like well width, barrier width and doping concentration on the field dependent multisubband electron mobility. We show that a large enhancement in mobility can be achieved through application of an external electric field by suitably choosing the material parameters.

Large enhancement of mobility is obtained through an external electric field for small barrier widths and doping concentrations in GaAs/InGaAs double quantum well structures. In the figure below we show that the enhancement of μ is large for small barrier widths (b in Å).Figure optionsDownload as PowerPoint slideHighlights
► We study the electric field induced enhancement in electron mobility in GaAs/InGaAs double quantum wells.
► Effect of structure parameters on the field induced multisubband mobility shows interesting results.
► The enhancement in mobility decreases as the barrier width and doping concentration increase.
► However, for different well widths the enhancement in mobility remains almost unchanged.