Suppression of ground-state optical recombination in the quantum Hall regime

The time evolution of optical recombination in the two-dimensional electron gas in GaAs/(Ga,Al)As heterostructures shows an anomalous increase at the Landau-level filling factor =1. Here we find that the radiative recombination rate is slowed by an order of magnitude and is commensurate with the quantum Hall effect. The inhibited electron-hole recombination is caused by localization and changes in the screening response of the electron gas, which leads to reduced electron-hole overlap and broadening of the density of states. These mechanisms are also manifest in a large increase in hole relaxation time at =1.