We report on a type-II InAs/GaSb strain layer superlattice photodetector using a nBn design with cutoff wavelength of similar to 4.8 mu m at 250 K. 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 2.3x10(-6) and 3.1x10(-4) A/cm(2) (V-b=0.1 V, T=77 K) for detectors with shallow isolation etch and conventional defined mesa, respectively. Quantum efficiency, responsivity, and spectral detectivity D-* of the device are presented. (C) 2008 American Vacuum Society.