Long wavelength interband cascade photodetector with type II InAs/GaSb superlattice absorber

We report on a long wavelength interband cascade photodetector with type II InAs/GaSb superlattice absorber. The device is a three-stage interband cascade structure. At 77 K, the 50% cutoff wavelength of the detector is 8.48 mu m and the peak photoresponse wavelength is 7.78 mu m. The peak responsivity is 0.93 A/W and the detectivity D* is 1.12 x 10(11) cm center dot Hz0.5/W for 7.78 mu m at -0.20 V. The detector can operate up to about 260 K. At 260 K, the 50% cutoff wavelength is 11.52 mu m, the peak responsivity is 0.78 A/W and the D* is 5.02 x 10(8) cm center dot Hz0.5/W for the peak wavelength of 10.39 mu m at -2.75 V. The dark current of the device is dominated by the diffusion current under both a small bias voltage of -0.2 V and a large one of -2.75 V for the temperature range of 120 to 260 K.