EXCITON PROPERTIES IN P-TYPE GAAS ALXGA1-XAS QUANTUM-WELLS IN THE HIGH DOPING REGIME/

An experimental study of optical properties of acceptor-doped quantum wells is presented. We have studied the effects of acceptor doping at concentration levels varying from 10(16) up to 10(19) cm(-3) using ste ady-state photoluminescence (PL) and PL excitation. Excitons can still be detected at high doping concentrations of 10(19) cm(-3), i.e., wel l above the degenerate limit hn these quantum wells. They survive most ly due to the inefficiency of screening in the two-dimensional (2D) sy stem. In addition to the dimensionality of the structure (2D or 3D), t he quenching of excitons is found to depend on doping type (n or p typ e) and the position of the doping (well or barrier doped). We also rep ort on hydrogen passivation effects on the same samples. As expected, there is a correlation between the results obtained, on the one hand, by decreasing the doping concentration and, on the other hand, increas ing the passivation time. Their behavior follows the same directions, except for the unexpected increase in the bound exciton population wit h increasing passivation.