  The effect of electron correlation on the photocurrent of self-assembled
InAs/InGaAs quantum dot infrared photo-detector (QDIPs) is studied. It is found
that Coulomb interaction and level mixing in the many-body open system lead to
double peaks associated with the intra-band transitions involving two lowest
levels of the quantum dot. Furthermore, the photocurrent is a nonlinear
function of the steady-state carrier density and it displays a plateau due to
Coulomb blockade.
