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 m response, and the devices also exhibit a strong photoresponse peak at 17 m 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 dark are 1.6 10 8 A/cm at 80 K and 1.55 A/cm at 300 K for 1-V applied bias. Measured values of peak responsivity and specific detectivity are 0.063 A/W and 2.4 10 cm Hz 2 W, respectively, under a bias of 2 V, at 80 K for the 6m response. For the 17m response, the measured values of peak responsivity and detectivity at 300 K are 0.032 A/W and 8.6 10 cm Hz 2 W under 1 V bias.