Properties of exciton states in GaAs/AlGaAs quantum wells in the presence of a quasi-two-dimensional electron gas

The changes in binding energy and oscillator strength of the exciton state due to the screening by a quasi-two-dimensional electron gas are calculated self-consistently in the approximation of noninteracting electrons and in the local field approximation. It is shown that the collapse of the bound state occurs at very low concentrations, N-s approximate to 5 x 10(9) cm(-2), which is a consequence of the inclusion of the nonlinearity of the response of the system to a Coulomb perturbation. The temperature dependence of the exciton collapse is investigated. The phase diagram of the dissociation of the given bound state is constructed, and the region in which it is possible to observe experimentally the temperature dependence of the exciton collapse is indicated. (C) 2002 MAIK "Nauka / Interperiodica".