Photovoltaic GaAs quantum well infrared detectors at 4.2 μm using indirect AlxGa1−x barriers

We have demonstrated the first bound to continuum state GaAs/AlxGa1−xAs quantum well infrared detector which has a peak response λp=4.2 μm in the center of the midwavelength (λ=3–5 μm) infrared band. Although the detector uses indirect AlxGa1−xAs barriers, excellent hot-electron transport and a high detectivity D*λ=1012 cm√Hz/W were achieved.