Photoluminescence hysteresis of the optically detected cyclotron-like resonance of a two-dimensional electron gas

A significant reduction of the two-dimensional electron gas (2DEG) density n(2D) in a modulation doped GaAs/AlGaAs quantum well is observed when the 2D-electrons are heated by microwave (mw) irradiation at 1.8 K. A dependence of n(2D) on the effective electron temperature T-e leads to a remarkable hysteresis of the optically detected dimensional magnetoplasma (cyclotronlike) resonance, namely, to a bistability of the 2DEG-free hole photoluminescence (PL) spectrum as the magnetic field is scanned back and forth. The n(2D) and T-e values for the nonequilibrium 2DEG are obtained from the PL spectrum analysis. The PL time-resolved study shows that n(2D) depends on the mw pulse duration and has a long recovery time similar to 10(-2) sec. This phenomenon is attributed to an increased vertical transport of the warm electrons out of the quantum well.