Effects of Coulomb blockade on the photocurrent in quantum dot infrared photodetectors

We present theoretical studies of the effects of Coulomb blockade on the photocurrent of quantum dot infrared photodetectors within the Anderson model with two localized levels coupled with the electromagnetic field. We use the Keldysh Green function method to calculate the photocurrent. The energy levels, on-site Coulomb energy, and coupling parameters between leads and quantum dot states, as functions of the applied field, are evaluated within an effective mass model. It is found that the Coulomb interaction and level mixing in the many-body open system lead to a double-peak spectrum for the intraband transition. The center of gravity of the spectrum is redshifted as the applied bias increases, which competes with the blueshift caused by the Stark effect. Furthermore, the photocurrent is found to be a nonlinear function of the steady-state electron density of the quantum dot, in sharp contrast to quantum well infrared photo-detectors.