Time-dependent heterointerfacial band bending and quasi-two-dimensional excitonic transport in GaAs structures

Using a time-resolved photoluminescence imaging technique with high spectral, temporal, and spatial resolution, we have directly measured the time- and carrier-density-dependent heterointerfacial band bending in (Formula presented) structures, and its influence on quasi-two-dimensional exciton transport. We find the spatially nonuniform band bending induced by laser excitation decays to its static, uniform band bending in (Formula presented) Further, we find that the observed transport is initially “driven” by a force originating from the spatially nonuniform band bending arising from photoexcited carrier screening of the built-in heterointerface field and is of very high mobility. This transport becomes diffusive asymptotically in time. © 1998 The American Physical Society.