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 steady-state photoluminescence (PL) and PL excitation. Excitons can still be detected at high doping concentrations of 10(19) cm(-3), i.e., well above the degenerate limit hn these quantum wells. They survive mostly due to the inefficiency of screening in the two-dimensional (2D) system. In addition to the dimensionality of the structure (2D or 3D), the quenching of excitons is found to depend on doping type (n or p type) and the position of the doping (well or barrier doped). We also report 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, increasing the passivation time. Their behavior follows the same directions, except for the unexpected increase in the bound exciton population with increasing passivation.