Electric field effects on electron mobility in n-AlGaAs/GaAs/AlGaAs single asymmetric quantum wells

Abstract

We calculated low-temperature electron mobility in n-AlGaAs/GaAs/AlGaAs single asymmetric quantum wells in the presence of a uniform electric field directed perpendicularly to the interfaces. The quantum well asymmetry is due to the doping profile (one-side modulation doping). Following a variational scheme, we solved both Schrödinger and Poisson equations simultaneously and the results were used to calculate the low-temperature (quasielastic) scattering rates. Only relevant scattering mechanisms were taken into account, namely ionized impurity, interface roughness, alloy disorder, and acoustic phonons (deformation potential and piezoelectric coupling). Our results show that both interface roughness and alloy disorder scattering rates are strongly dependent upon the electric field strength. We also show that there are interesting changes in the dominance of the mobility among different scattering processes, which leads to the formation of a maximum in the mobility dependence on the electric field strength. In general, this maximum occurs for some positive electric field (antiparallel to growth direction) and it indicates that longitudinal electric fields can be used to dislocate the electron wave function, enhancing in turn the two-dimensional electron mobility in such quantum wells.