Recent Results on III–V Superlattices and Quantum Well Structures

Abstract

We present recent studies of four different III–V quantum well structures, which illustrate the diversification of to-day’s material science. We examine the controversal problem of the band offsets in the GaAs-Ga_1-x Al_xAs system from the excitation spectroscopy of double step quantum wells. For this system, we discuss also the Stokes shift of a few meY’s which is often observed between the luminescence and absorption peaks in terms of exciton trapping on individual interface fluctuations. In OaSb-AlSb strained layer superlattices, we have investigated the in-plane dispersion relations of the valence subbands from interband magneto-absorption experiments. Our results exhibit large qualitative differences with respect to the GaAs-Al_xGa_1-xAs case. The InAs-GaAs superlattice grown on an InP substrate is another interesting system in which the properties of large built-in strains and very thin layers come into play. We have performed calculations of the band structure of these pseudo alloy superlattices, which we compare to our low-temperature luminescence data We have also studied theoretically a new consequence of the spatial separation of the electron and hole wave functions in InAs-GaSb superlattices, that is a macroscopic transient photovoltage which presents analogies with the piezo electric effect.