Surface leakage investigation via gated type-II InAs/GaSb long-wavelength infrared photodetectors

By using gating technique, surface leakage generated by SiO₂ passivation in long-wavelength infrared type-II superlattice photodetector is suppressed, and different surface leakage mechanisms are disclosed. By reducing the SiO₂ passivation layer thickness, the saturated gated bias is reduced to -4.5 V. At 77 K, dark current densities of gated devices are reduced by more than 2 orders of magnitude, with 3071 Ω cm² differential-resistance-area product at -100 mV. With quantum efficiency of 50, the 11μm 50 cut-off gated photodiode has a specific detectivity of 7 × 10¹¹ Jones, and the detectivity stays above 2 × 10¹¹ Jones from 0 to -500 mV operation bias.