Heterojunction wavelength-tailorable far-infrared photodetectors with response out to 70 mm

Results are presented on the performance of a heterojunction interfacial workfunction internal photoemission ~HEIWIP! wavelength-tailorable detector. The detection mechanism is based on free-carrier absorption in the heavily doped emitter regions and internal emission across a workfunction barrier caused by the band gap offset at the heterojunction. The HEIWIP detectors have the high responsivity of free-carrier absorption detectors and the low dark current of quantum well infrared photodector type detectors. For a 7062 cutoff wavelength detector, a responsivity of 11 A/W and a D*51310 cmAHz/W with a photocurrent efficiency of 24% was observed at 20 mm. From the 300 K background photocurrent, the background limited performance ~BLIP! temperature for this HEIWIP detector was estimated to be 15 K. This HEIWIP detector provides an exciting approach to far-infrared detection. © 2001 American Institute of Physics. @DOI: 10.1063/1.1361283#