nBn detectors based on InAs∕GaSb type-II strain layer superlattice

We report on a type-II InAs∕GaSb strain layer superlattice photodetector using a nBn design with cutoff wavelength of ∼4.8μm at 250K. The surface component of dark current was eliminated. Using a shallow isolation etch, low temperature dark current was reduced by two orders of magnitude compared with conventional photodiode processing. Dark current densities were equal to 2.3×10−6 and 3.1×10−4A∕cm2 (Vb=0.1V, T=77K) for detectors with shallow isolation etch and conventional defined mesa, respectively. Quantum efficiency, responsivity, and spectral detectivity D* of the device are presented.