Stress effects on the binding energy of shallow-donor impurities in symmetricalGaAs/AlGaAs double quantum-well wires

Abstract

The effects of applied compressive stress on the binding energies of shallow-donorimpurity states with a finite confinement potential in symmetrical GaAs/AlGaAsdouble quantum-well wires (DQWWs) are studied theoretically using a variationalprocedure within the effective-mass approximation. Significant results for different wireand barrier widths, shallow-donor impurity positions, and compressive stressalong the growth direction of the structure are obtained taking into account theΓ–X crossover and the image charge effects in the calculations. Our results show that thebinding energy does not change appreciably with the size of the wire and barrier, or withthe donor ion position. We also find that for stress values up to 13.5 kbar, the bindingenergy increases linearly with stress, while for stress values greater than 13.5 kbar, thebinding energies show nonlinear behavior. Moreover, in the limit of double quantumwells (DQWs), our binding energy agrees with previously reported results. It ispointed out that compressive stress is an important factor in studies of the bindingenergies of shallow-donor impurity states in symmetrical GaAs/AlGaAs DQWWs.