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Electron transport studies on In(0.30)Ga(0.70)As/GaAs-quantum-well infrared photodetectors using time-resolved photocurrent measurements

Elektronen-Transportuntersuchungen an In(0.30)Ga(0.70)As/GaAs Quantenfilm-Infrarot-Photodetektoren mittels zeitaufgelöster Photostrommessungen
: Steinkogler, S.; Schneider, H.; Rehm, R.; Walther, M.; Koidl, P.


Applied Physics Letters 81 (2002), Nr.18, S.3401-3403
ISSN: 0003-6951
ISSN: 1077-3118
Fraunhofer IAF ()
QWIP; infrared detector; Infrarotdetektor; quantum well; Quantenfilm; space charge; Raumladung; continous waves measurement; photoinduced space charge; photoconductive gain

We report on the time-resolved photocurrent response on an InGaAs/GaAs quantum-well infrared photodetector stimulated by infrared fs-laser pulses (~9 µm wavelength). We observe two dynamic photocurrent components, which are driven by the optical excitation and by the photoinduced space charge, respectively. The ratio of the time-averaged values of these two components allows us to determine the photoconductive gain. These gain values exhibit a good quantitative agreement with the gain obtained from continuous waves measurements of the peak responsivity. Furthermore, we present a detailed study of the decay time constant of the slow component as a function of the temperature and the bias voltage and compare our results with a recent theoretical model.