Photovoltaic quantum-dot infrared detectors

We demonstrate the operation of photovoltaic quantum-dot infrared detectors fabricated from (In, Ga)As/GaAs heterostructures. These detectors are sensitive to normal incidence light. At zero bias, we obtain a low-temperature (78 K) peak detectivity of 2×108 cm Hz1/2/W, with a responsivity of 1 mA/W at a wavelength of 13 μm for one of the devices. The photovoltaic effect in our detectors is a result of the intrinsic inversion asymmetry of the band structure of self-formed quantum dots. A compensation voltage of 18 mV is measured.