HGCDTE DUAL-BAND INFRARED PHOTODIODES GROWN BY MOLECULAR-BEAM EPITAXY

We report the demonstration of an all molecular beam epitaxy HgCdTe bias-selectable dual-band infrared photodetector. The mesa device, an n-p-n three layer HgCdTe heterostructure, was in situ doped with arsenic and indium for p- and n-type doping. The device design is similar to a heterostructure floating base transistor. The feasibility of the two-color bias-switchable detector was demonstrated by obtaining backside illuminated spectrally pure dual-band detection at 77 K. Wavelength cutoff (lambda-co) selection to 5.2-mu-m with 60% quantum efficiency (QE) was obtained by applying a negative bias of -250 meV, and to lambda-co = 7.9-mu-m with 36% QE by applying a positive bias of 250 meV. The current-voltage characteristics of this device can be described in terms of a simple back-to-back diode model.