THz intersubband dynamics in p-Si/SiGe quantum well emitter structures

We report time‐resolved (ps) studies of the dynamics of intersubband transitions in p‐Si/SiGe multi‐quantum well structures in the FIR regime, ħω < ħωLO, utilizing the Dutch free electron laser, FELIX. The calculated scattering rates have been included in a rate equation model of the transient FIR intersubband absorption, and are in excellent agreement with our degenerate pump‐probe spectroscopy measurements where after an initial rise time determined by the resolution of our measurement, we determine a decay time of ∼10 ps. In strong contrast to similar measurements on p‐GaAs quantum wells, this is found to be approximately constant in the temperature range from 4 to 100 K, in good agreement with the predictions of alloy scattering in the Si0.7Ge0.3 wells.