The investigations to eliminate the bias dependency of quantum efficiency of InGaAsSb nBn photodetectors for extended short wavelength infrared detection

We report our investigations to eliminate the bias dependency of quantum efficiency of nBn devices based on InGaAsSb bulk alloy aimed for extended short wavelength detection. Both a p-type doped AlGaSb barrier and a p-type doped top contact layer were employed. The 9 × 1015cm-3p-type doping of AlGaSb barrier slightly improves the bias dependency of quantum efficiency of nBn devices. The using of p-type doped top contact layer completely eliminated the band offset induced bias dependency of quantum efficiency and a 2.2% variation of quantum efficiency as applied reverse bias increases was discussed in terms of the effect of surface depletion region and junction depletion region.