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A novel device-resonant tunneling quantum-dot infrared photodetector-has been investigated theoretically and experimentally. In this device, the transport of dark current and photocurrent are separated by the incorporation of a double barrier resonant tunnel heterostructure with each quantum-dot layer of the device. The devices with In0.4Ga0.6As-GaAs quantum dots are grown by molecular beam epitaxy. We have characterized devices designed for ∼6 μm response, and the devices also exhibit a strong photoresponse peak at ∼17 μm at 300 K due to transitions from the dot excited states. The dark currents in the tunnel devices are almost two orders of magnitude smaller than those in conventional devices. Measured values of Jdark are 1.6×10-8 A/cm2 at 80 K and 1.55 A/cm2 at 300 K for 1-V applied bias. Measured values of peak responsivity and specific detectivity D* are 0.063 A/W and 2.4×1010 cm·Hz12//W, respectively, under a bias of 2 V, at 80 K for the 6-μm response. For the 17-μm response, the measured values of peak responsivity and detectivity at 300 K are 0.032 A/W and 8.6×106 cm·Hz12//W under 1 V bias.