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Low-power photocurrent nonlinearity in quantum well infrared detectors

Nichtlinearität des Photostroms bei niedrigen Leistungen in Quantum well-Intersubband-Infrarotdetektoren


Applied Physics Letters 71 (1997), No.14, pp.2011-2013
ISSN: 0003-6951
ISSN: 1077-3118
Journal Article
Fraunhofer IAF ()
GaAs/AlGaAs; infrared; Infrarot; photodetector; Photodetektor; quantum wells

We report on the intensity dependence of the responsivity in quantum well infrared photodetectors (QWIP). A strong reduction of the responsivity is observed already at small excitation powers for a QWIP with N=4 periods. This nonlinearity is caused by a partial screening of the electric field across the main part of the active region. The intensity dependence is analyzed using a phenomenological approach, which allows us to calculate the nonlinearity from the measured dark current and responsivity. Applying this approach to a background-limited 50 period QWIP, we find that the nonlinearity is already present below 1 mW cm(-2) which is less than the thermal background.