Near- and mid-infrared detection using GaAs∕InxGa1−xAs∕InyGa1−yAs multiple step quantum wells

A dual-band multiple-quantum-well infrared photodetector capable of simultaneously detecting wavelengths near 0.9 μm and 10 μm has been fabricated using GaAs∕InGaAs step quantum wells. The detection of the near (0.82–0.95 μm)- and mid (9–11 μm)-infrared wavelength bands was achieved using interband and intersubband transitions. The measured peak responsivities of the near- and mid-infrared bands were 0.4 A∕W and 1 A∕W, respectively, at 0.8 V bias across the device. The broken symmetry of the step quantum well allows transitions from the ground states of heavy and light holes to the first-excited electron state allowing the photoexcited carriers to be efficiently collected. The estimated values of the detectivities for near- and mid-infrared bands at 40 K and 0.8 V bias are approximately 4.5×109cm(Hz)1∕2∕W and 1.1×1010cm(Hz)1∕2∕W, respectively.