The effects of doping on InAs/In0.15Ga0.85As quantum dots-in-well infrared photodetectors have been investigated by measuring the dark current, photocurrent, spectral response, responsivity, and detectivity. The dark current increased monotonically as a function of the doping level in the dots. The photocurrent too increased with the increase in the doping level. By measuring the background limited infrared photodetector temperature, we find that the optimum sheet doping concentration in these detectors is n = 3 x 10(10) cm(2) (corresponding to about le/dot). These results were corroborated by measurement of responsivity and generation-recombination noise limited detectivity of these detectors. (c) 2006 American Vacuum Society.