Interband cascade detectors with room temperature photovoltaic operation

We investigated mid-infrared interband cascade laser structures as photodetectors, which are sensitive to normal incidence and operate in photovoltaic mode at room temperature. The proposed operation principle of these interband cascade detectors is based on the unique combination of interband photoexcitation and the much faster intersubband relaxation as well as interband tunneling recombination, which allows for the efficient collection of the photoexcited carriers. Peak responsivity and detectivity of 21 mA/W and 7.1×108cmHz1∕2∕W at λ=4.0μm are obtained for a device with cutoff wavelength of 4.4μm. Peak responsivity and detectivity of 46 mA/W and 1.4×109cmHz1∕2∕W at λ=3.0μm are obtained for another device with cutoff wavelength of 3.3μm. These detectors exhibit low noise (4.8×10−13A∕Hz1∕2) and a large product of the differential resistance and active area (19Ωcm2) at room temperature.