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 Si3N4 passivation, the R0A of the superlattice detector decreased from 2.8×105Ωcm2 to 12Ωcm2 at 80K after a process of rapid thermal annealing (RTA) at 250°C for 60s. Excessive surface charge of 6.15×1012cm-2 was measured from a gate-controlled structure. Meanwhile, the SiO2 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. SiO2 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/cm2 and the best R0A value as 13 Ωcm2. We simulated four main dark current mechanisms. The result shows that the intrinsic carrier density is extracted to be 3.5E15 cm-3 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.