A multicolor quantum dot intersublevel detector with photoresponse in the terahertz range

An In0.4Ga0.6As∕GaAs multi quantum-dot layer intersublevel detector with multicolor detection is demonstrated. The n-type doping in the dots is carefully adjusted during molecular beam epitaxy of the device heterostructure to control the dark current and the occupation of the dot states as a function of temperature. The device demonstrates several photoresponse peaks in the 3–13 and 20–55μm (15–5.4THz) ranges. At 150K, the response in the terahertz range has a peak responsivity of 0.05A∕W and specific detectivity D* of 2×107 Jones for an applied bias of −2V.