Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 82: Ultrafast Phenomena

HL 82.3: Talk

Thursday, March 17, 2011, 15:00–15:15, POT 251

Time-resolved photoluminescence from GaAs/AlGaAs multiquantum wells quenched by pulsed mid-infrared radiation — •Sabine Zybell, Harald Schneider, Stephan Winnerl, and Manfred Helm — Helmholtz-Zentrum Dresden-Rossendorf, Germany

Several groups have demonstrated the suppression of photoluminescence (PL) from semiconductor quantum wells (QWs) by intense mid-infrared radiation (MIR). Since most of the previous studies are done on time-integrated PL the ultrafast changes in the radiative state population are not well understood. We present a detailed study on time-resolved PL from an undoped GaAs/AlGaAs QW sample quenched by MIR pulses from a free-electron laser, which was tuned to the intersubband transition (ISBT) energy. At the arrival time of the MIR pulse a clear sharp dip appears in the PL transient. Free carrier absorption and ISBT are the two processes that take place under MIR excitation and result in an abrupt drop of the radiative state population and consequently in an ultrafast quenching of the PL. Performing polarization sensitive measurements, we were able to discriminate the contributions of free carrier absorption from that of ISBT. A quantitative analysis of the PL dip depth and recovery time as a function of MIR fluence was done using a model based on rate equations.