Short wavelength (1–4 μm) infrared detectors using intersubband transitions in GaAs-based quantum wells

We explore the possibility of covering the short wavelength infrared region using intersubband transitions in GaAs-based quantum wells. We investigate InGaAs wells with AlAs thin confining barriers. For this type of double-barrier resonant-final-state detectors, the dark current decreases with increasing detection wavelength. Photocurrents due to intersubband transition are observed down to a wavelength of about 1 μm. The spectra also reveal interesting physical effects apparently related to the indirect band minima at the X point. The responsivity for the 3–4 μmm detectors reaches up to 0.01 A/W; and the background limited temperature is in the range of 80–100 K.