Influence of the interface corrugation on the subband dispersions and the optical properties of (113)-oriented GaAs/AlAs superlattices

We report on the influence of the interface corrugation in (113)-grown GaAs/AlAs superlattices on their band-edge optical properties both in theory and experiment. We calculate the subband dispersions and the optical anisotropies in a multiband k . p formalism. The dominating contribution to the optical anisotropies is found to be due to the intrinsic properties of the valence-band structure. The corrugation modifies the density of states only slightly, giving no evidence of a quantum-win behavior. By comparing the calculation with the experimental optical anisotropy, we can estimate the corrugation height to be at most 2 monolayers. The experiments show that deviations from the regular corrugation lead to an anisotropic interface disorder. This gives rise to an enhanced anisotropy of the band-edge states, which was so far attributed to the corrugation itself. The luminescence of the localized type-I states at the band-edge show an enhanced optical anisotropy in comparison to the luminescence of the extended states, revealing the anisotropic nature of their localization sites. In type-II samples, deeply localized, isolated type-I states (Gamma quantum boxes) dominate the luminescence at short delays after pulsed excitation and at higher lattice temperatures or excitation densities, due to their strong radiative decay compared to the type-II states. These quantum boxes are observed individually by high spatial and spectral resolution.