TIME-RESOLVED OPTICAL RECOMBINATION IN THE QUANTUM HALL REGIME

Optical recombination in a 2D electron gas shows anomalous time-dependence in the quantum Hall regime at nu = 1. The recombination rate in GaAs/(Ga, Al)As structures is slowed by as much as an order of magnitude. This effect is attributed to reduced overlap of electron and hole caused by reduced screening in the localized regime. The suppression of the E0 ground-state recombination leads to a transfer of intensity into the E1 emission line associated with electrons in the excited-state subband. It is found that the decay time of the E1 emission line increases toward the low-energy side of the peak, and the effect becomes weaker outside nu = 1.