GaAs/InGaAs quantum well infrared photodetector with a cutoff wavelength at 35 mu m

GaAs/InGaAs far-infrared quantum well photodetectors based on a bound-to-co ntinuum intersubband transition with a (zero response) cutoff wavelength of 35 mu m are reported. A peak responsivity of 0.45 A/W and detectivity of 6 .0 x 10(9) cm root Hz/W at a wavelength of 31 mu m and a temperature of 4.2 K have been experimentally achieved. Infrared response was observed at tem peratures up to 18 K, A calculated responsivity spectrum using a bound-to-c ontinuum line shape corrected for phonon absorption is fitted to the experi mental response. The calculated line shape without absorption gives a cutof f wavelength of 38 mu m with a peak responsivity of 0.50 A/W and a detectiv ity of 6.6 x 10(9) cm root Hz/W at 32 mu m. (C) 2000 American Institute of Physics. [S0003-6951(00)00931-1].