Dynamics of microwave-induced processes in photoexcited GaAs/AlGaAs heterostructures

Photoluminescence (PL) of high-quality GaAs/AlGaAs-based heterostructures (HS) shows a remarkable timedependent response to microwave irradiation pulses at temperature 2 K. The mw-frequency was 36 GHz and the modulation pulse widths varied in a wide range. Sharp PL intensity flashes (reaching 100 fold enhancement) at the leading or/and trailing mw-pulse edges are observed. The transient PL response exhibits a complex interplay of various mw-induced physical processes: electron heating, electron and exciton density changes as well as an interaction of electrons, holes and excitons with non-equilibrium acoustic phonons that are emitted by the mw-heated 2DEG. It is noted that in commonly studied cw, mw-induced PL (or resistivity) modulation, the observed (cw) effects are determined by a combination of these processes. We developed a model that considers the instantaneous mw-induced electron heating and following relaxation of the photoexcited electrons, excitons and acoustic phonon flux. Using this model we simulate various types of mw-induced PL transients observed in undoped HS's as well as in HS's that contain a 2DEG. These simulations prove that non-equilibrium acoustic phonons play an important role in the mw-induced PL dynamics.