Spatial Optimization of Modulation Doping in P-I-P QDIPs: Towards Achieving Higher Operating Temperature

We report short wavelength infrared (SWIR) photodetectors using multi-stacked modulation doped Indium-Arsenide (InAs) self-assembled quantum dots (QDs). The detriments of direct doping on the energy levels of InAs QDs have been eliminated by choosing modulation doping. We have considered three P-I-P Indium Arsenide/Gallium Arsenide (InAs/GaAs) quantum dot infrared photodetector (QDIP) heterostructures in which a thin (3 nm) P-doped GaAs layer is introduced at a distance of 7, 12 and 17 nm away from each InAs dot layer respectively. The structures have been analyzed for their morphological and optical characteristics and an optimum separation between the active layer and modulation doped layer has been achieved. The fabricated single pixel detectors exhibit a broad spectral response from 1 to 3.5 μm in the SWIR region for all the samples. The infrared photocurrent survives up to a maximum temperature of 200K for the optimized device with a peak responsivity of 1.439 A/W at wavelength λ = 1.77 μm and temperature T = 200 K.