OPTICAL AND TRANSPORT STUDIES OF HIGHLY ACCEPTOR-DOPED GAAS ALGAAS QUANTUM-WELLS/

We present a theoretical and experimental study of the properties of h ighly acceptor-doped quantum wells (QWs), with doping levels varying f rom 9 x 10(9) to 6 x 10(12) cm(-2). From variable temperature Hall mea surements it is found that the temperature dependence of the mobility differs remarkably from p-type bulk GaAs, as well as n-type QWs. For t he moderately doped (N-A < 3 x 10(11) cm(-2)) sample, the mobility is almost constant with temperature up to similar to 100 K, while the 2D hopping conduction dominates in the same temperature range for the deg enerate samples. The activation mechanism involved in the investigated structure can be understood in terms of the change of the subband str ucture due to the central doping. Steady-state photoluminescence (PL) and PL excitation results ae compared with theoretical predictions inv olving exchange and correlation effects for the electron-hole system a nd their interaction with acceptor ions. We finally report on the surv ival of the excitons well above the degenerate limit, due to inefficie nt screening in the 2D case.