Effect of sidewall surface recombination on the quantum efficiency in a Y2O3 passivated gated type-II InAs/GaSb long-infrared photodetector array

Y2O3 was applied to passivate a long-wavelength infrared type-II superlattice gated photodetector array with 50% cut-off wavelength at 11 μm, resulting in a saturated gate bias that was 3 times lower than in a SiO2 passivated array. Besides effectively suppressing surface leakage, gating technique exhibited its ability to enhance the quantum efficiency of 100 × 100 μm size mesa from 51% to 57% by suppressing sidewall surface recombination. At 77 K, the gated photodetector showed dark current density and resistance-area product at −300 mV of 2.5 × 10−5 A/cm2 and 1.3 × 104 Ω cm2, respectively, and a specific detectivity of 1.4 × 1012 Jones.