Low-temperature-grown GaAs quantum wells: Femtosecond nonlinear optical and parallel-field transport studies

We find that GaAs-AlGaAs quantum wells grown at low temperature (300 °C) by molecular beam epitaxy are nearly semi-insulating and exhibit a broadened excitonic resonance. Studies of the femtosecond time-resolved nonlinear optical saturation response and parallel-field transport properties indicate that a subpicosecond nonradiative decay dominates the carrier recombination of this material. Annealing of low-temperature-grown quantum wells causes the arsenic point defects to form arsenic metallic precipitates within the quantum wells and up-shifts the absorption edge.