Temperature dependence of microwave photoresistance in 2D electron systems

We report on studies of the temperature dependence of microwave- induced resistance oscillations in a high-mobility two- dimensional electron system. We find that the oscillations decay exponentially with increasing temperature, as $\exp(- \alpha T^2)$, where $\alpha$ scales with the inverse magnetic field. This observation suggests that the temperature dependence originates {\em primarily} from the modification of the single particle lifetime, likely through electron-electron interaction effects. The relevance of our findings to existing theories will be discussed.