INFLUENCE OF THE INTERFACE CORRUGATION ON THE SUBBAND DISPERSIONS ANDTHE 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 o ptical anisotropies in a multiband k . p formalism. The dominating con tribution to the optical anisotropies is found to be due to the intrin sic 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 optic al anisotropy, we can estimate the corrugation height to be at most 2 monolayers. The experiments show that deviations from the regular corr ugation lead to an anisotropic interface disorder. This gives rise to an enhanced anisotropy of the band-edge states, which was so far attri buted to the corrugation itself. The luminescence of the localized typ e-I states at the band-edge show an enhanced optical anisotropy in com parison to the luminescence of the extended states, revealing the anis otropic 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 lat tice temperatures or excitation densities, due to their strong radiati ve decay compared to the type-II states. These quantum boxes are obser ved individually by high spatial and spectral resolution.