Effect of low-temperature illumination on quantum lifetime in GaAs quantum wells*

It is well known that low temperature illumination of a high-mobility two-dimensional electron gas hosted in GaAs quantum wells can greatly improve the quality of magnetotransport data even when the carrier density and mobility remain essentially unchanged. In high magnetic fields, this improvement is evident from the appearance or better development of fractional quantum Hall states as well as stripe and bubble phases. However, what exactly drives this improvement remain unclear. Here, we investigate the effect of illumination on microwave photoresistance in low magnetic fields. We find that the amplitude of microwave-induced resistance oscillations increases dramatically after low-temperature illumination. Dingle analysis reveals that illumination leads to a substantial increase in the single particle lifetime.