Reduction of surface leakage current in InAs/GaSb strained layer long wavelength superlattice detectors using SU-8 passivation

We report on SU-8 passivation for reducing surface leakage current in type-II InAs/GaSb strained layer superlattice detectors (λ100% cut-off∼12 μm). The electrical behavior of SU-8 passivated and unpassivated devices was compared for devices with variable mesa sizes. Dark current was reduced by more than one order of magnitude for the small area (50 μm×50 μm) passivated diode at 77 K. The surface resistivity, the responsivity and specific detectivity were measured for SU-8 passivated devices and are equal to 204 Ω cm, 0.58 A/W and 3.49×109 Jones, respectively (77 K).