Bistable charge states in a photoexcited quasi-two-dimensional electron-hole system

The luminescence spectra of GaAs/AlGaAs quantum wells (QWs) with low-densit y quasi-two-dimensional electron and hole channels were studied. It was dem onstrated that, at temperatures below some critical value (T-c similar to 3 0 K) and for an excitation power lying in a certain temperature-dependent r ange, two metastable charge states with two-dimensional charge densities di ffering in both magnitude and sign can occur in the system under the same c onditions. The obtained experimental data agree well with the mathematical model allowing for the transfer of photoexcited carriers to the barrier fol lowed by their tunneling into QW. (C) 2000 MAIK "Nauka/Interperiodica".