Resonant tunneling via stress-induced valence-band mixings in GaAs-(Ga,Al)As asymmetrical double quantum wells
Résumé
Optical band-to-band transition energies and oscillator strengths are calculated in the envelope-function approximation, for GaAs-(Ga,Al)As asymmetrically coupled double quantum wells, subjected to externally applied in-plane uniaxial stress. It is shown that the spatial probability distribution of holes should be strongly affected by this perturbation, due to the superimposition of stress-induced mixings of valence states, together with tunneling effects across the thin intermediate barrier. As a consequence, the electron and hole envelope functions overlap, and thus the probability of a given subband-to-subband transition is expected to be modified. Since simple, parity-related selection rules are no longer in effect in such structures, due to the lack of symmetry, the optical transitions are expected to shift, appear, or disappear, depending on the initial degree of coupling between the quantum wells, and on the magnitude of the stress.