Variations in the optical spectra of the ground-state exciton in GaAs quantum wells induced by uniaxial stress

The effects of uniaxial stress on the energies and the absorption linewidths of ground-state exciton transitions in GaAs/${\mathrm{Al}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As quantum wells have been investigated both theoretically and experimentally. The valence subbands and the corresponding wave functions were analyzed at the Brillouin-zone center by solving a 4×4 Luttinger-Kohn Hamiltonian in conjunction with a 4×4 strain Hamiltonian in the spin J=(3/2 basis. The ground-state binding energy of the exciton was calculated variationally. Contributions to the absorption linewidths were calculated for various scattering mechanisms (alloy disorder, interface roughness, piezoelectric, and deformation potentials) at low temperatures. Also, oscillator strengths were studied. We found that the absorption linewidth decreases as stress (∥[100]) increases, and the dominant mechanism for this result is alloy fluctuation. A comparison between theoretical predictions and experimental results is presented.