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Photoluminescence dynamics in GaAs/AlGaAs quantum wells under pulsed intersubband excitation

: Zybell, S.; Schneider, H.; Winnerl, S.; Wagner, M.; Köhler, K.; Helm, M.


Applied Physics Letters 99 (2011), Nr.4, Art.041103, 3 S.
ISSN: 0003-6951 (Print)
ISSN: 1077-3118
ISSN: 1931-9401 (online)
Fraunhofer IAF ()

We investigate the time-resolved photoluminescence (PL) dynamics of an undoped GaAs/AlGaAs multiple quantum well under mid-infrared (MIR) irradiation. A time-delayed MIR laser pulse from a free-electron laser, tuned to the intersubband transition energy of the quantum well, induces temporal quenching of the PL intensity with subsequent recovery. The experimental data can be accurately described by a simple rate-equation model, which accounts for the cooling of the non-radiative states to radiative states. By performing polarization sensitive measurements, we are able to discriminate the contributions of free-carrier absorption from that of intersubband absorption, where the latter is about 50 times more efficient.