Detection wavelength of quantum-well infrared photodetectors

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Abstract
Long wavelength infrared detection using intersubband transitions has been progressing rapidly in recent years. One advantage of the quantum‐well infrared photodetectors is the wavelength tunability as a function of their structural parameters. In this work, we have performed a systematic calculation on the detection wavelength, the absorption linewidth, and the oscillator strength of a typical GaAs/Al x Ga1−x As multiple‐quantum‐well photodetector, with aluminum molar ratio in the barriers ranging from 0.14 to 0.42 and the quantum‐well width ranging from 20 to 70 Å. We found that within these material parameters, the detection wavelength can be varied from 5 to over 25 μm. In addition, we also discuss the photoconductive gain of the detectors with respect to the energies of the final state of the optical transition and the satellite valleys of the detector material.