As a promising candidate for the next generation of infrared detection and imaging, more and more studies are focused on the type-II InAs/GaSb superlattice recently. In this paper, we studied different passivation techniques and the dielectric film-semiconductor interface properties for InAs/GaSb superlattice photodetectors. We found that with Si<sub>3</sub>N<sub>4</sub> passivation, the R<sub>0</sub>A of the superlattice detector decreased from 2.8×10<sup>5</sup>Ωcm<sup>2</sup> to 12Ωcm<sup>2</sup> at 80K after a process of rapid thermal annealing (RTA) at 250°C for 60s. Excessive surface charge of 6.15×10<sup>12</sup>cm<sup>-2</sup> was measured from a gate-controlled structure. Meanwhile, the SiO<sub>2</sub> passivated devices can sustain its electrical performance after the RTA process.
Dark current characteristics of long wavelength InAs/GaSb superlattice (SL) detectors have been studied in this paper.
The long wavelength SL structure consists of periodic 14 monolayers (MLs) InAs and 7 MLs GaSb with 50% cutoff
wavelength around 11 μm. Three InAs/GaSb superlattice detectors of PBIN structure were grown at different
temperatures. Wet chemical etching was used to define device mesa. SiO<sub>2</sub> was used for device passivation to suppress the sidewall leakage current. Electron barriers were inserted between the absorber region and P-type conducting region to reduce the bulk dark current. The detectors grown at 380oC have the lowest dark current densities as 0.01A/cm<sup>2</sup> and the best R0A value as 13 Ωcm<sup>2</sup>. We simulated four main dark current mechanisms. The result shows that the intrinsic carrier density is extracted to be 3.5E15 cm<sup>-3</sup> which matches the C-V measurement very well. And the GR and trap assisted tunnel current dominate the dark current of the device due to the large trap densities and short GR lifetimes.