Modulation-doped double-barrier quantum well infrared detectors for photovoltaic operation in 3-5 μm

With the aim of combining the mid-infrared detection with the photovoltaic (PV) mode operation, we present in this work a series of modulation-doped (MD) quantum well infrared photodetectors (QWIPs) based on AlGaAs-AlAs-GaAs, that exhibit a remarkable responsivity at zero bias (0.05 A/W at 25 K). Since the PV signal is strongly dependent on the symmetry of the potential profile, we have varied the dopant location in the AlGaAs barriers. The responsivity and detectivity of the MD devices, in particular for the MD detector with the dopant at the substrate side AlGaAs barrier, seem to be higher to those of a well-doped sample of nominally the same structure, also considered for comparison. Self-consistent calculations for the potential profile of the MD devices are compared with experiment.