ANISOTROPIC QUANTUM BOXES IN CORRUGATED SUPERLATTICES

We report on the observation of isolated, anisotropically confined ele ctronic states of the type-I transition in (113)-grown, type-II GaAs/A lAs superlattices. They are formed by fluctuations of the periodic int erface corrugation. Electronic states related to the X conduction-band minimum act, at elevated temperatures, as a transport channel to thes e Gamma quantum boxes. The extremely narrow emission lines of the quan tum boxes show an enhanced optical anisotropy compared to the luminesc ence of the extended states, revealing the anisotropic nature of the l ocalization sites. This is confirmed by a comparison of the experiment al luminescence energy and anisotropy with the results of a multiband k . p calculation for a quantum wire model system.