A resonant tunneling quantum-dot infrared photodetector

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 In_0.4Ga_0.6As-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 J_dark 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.