INGAAS/ALGAAS QUANTUM-WELL INFRARED PHOTODETECTORS WITH 3-5 MU-M RESPONSE

We demonstrate the detection of mid-wavelength infrared (similar to 3-5 mu m) radiation by Intersubband transitions in multiple quantum well structures. These devices exploit the large conduction band offset between InxGa1-xAs and AlyGa1-yAs in order to obtain shorter wavelength detection than is available with the more conventional AlyGa1-yAs/GaAs infrared photodetector technology. The peak detector response is shifted from 4.8 to 4.3 mu m by increasing the indium fraction from x = 0.05 to x = 0.20, while simultaneously decreasing the well width to keep the first excited eigenstate near the top of the wells. These: detectors can be integrated with AlyGa1-yAs/GaAs long-wavelength (8-12 mu m) infrared quantum well detectors for multi-band imaging applications.