Space-charge effects in photovoltaic double barrier quantum well infrared detectors.

We show that the spatial distribution of the dopants strongly influences the transport asymmetry and the photovoltage observed in double barrier quantum well intersubband photodetectors. This influence can be quantitatively explained by the local space-charge fields arising from an asymmetry of the doping profile with respect to the well centers. The resulting transport model correctly predicts both the observed transport asymmetry of the photocurrent and the opposite asymmetry of the dark current.