Photoluminescence dynamics of GaAs/AlAs quantum wells modulated by surface acoustic waves

We have investigated the dynamics of photoluminescence (PL) of GaAs/AlAs quantum wells under strain and piezoelectric modulation introduced by a surface acoustic wave (SAW). Measurements performed using a microscopic excitation spot show that the efficiency of PL quenching due to exciton ionization and the subsequent sweeping of free electrons and holes by piezoelectric potential varies significantly with quantum well thickness. This variation is attributed to the well-thickness dependence of carrier mobility and diffusivity. The relative timing between carrier generation pulse and SAW-induced band structure modulation also changes the delay of PL quenching and PL decay time under the SAW field.