BARRIER THICKNESS DEPENDENCE OF THE PHOTOSCREENING OF THE PIEZOELECTRIC FIELD IN (111)-ORIENTATED GAAS-INXGA1-XAS DOUBLE-QUANTUM WELLS

In this article we present low temperature photoluminescence spectra f rom a series of (111) orientated GaAs-InxGa1-xAs double quantum well s tructures with differing barrier thicknesses. We demonstrate an enhanc ement in the carrier screening of the strain induced internal piezoele ctric field by photocreated electrons and holes as the barrier thickne ss is increased. The enhanced screening arises from an increase in the spatial separation of the electron and hole populations. Additionally , we observed a photoinduced spatial transfer of the second lowest lyi ng heavy hole level. This spatial transfer is a strong function of the electron and hole separation and limits the amount of the optically p umped ''blue'' shift of the lowest energy intersubband transition. (C) 1998 American Institute of Physics.