Mid-wavelength infrared planar junction photodetector based on InAs/GaSb Type-Ⅱ superlattices

Abstract In this paper, a planar junction mid-wavelength infrared (MWIR) photodetector based on an InAs/GaSb type-Ⅱ superlattices (T2SLs) is reported. The Intrinsic-πMN superlattices was grown by the molecular beam epitaxy (MBE), followed with a ZnS layer grown by the chemical vapor deposition (CVD). The p-type contact layer was constructed by thermal diffusion in the undoped superlattices. The Zinc atom was successfully realised into the superlattice and a PπMN T2SL structure was constructed. Furthermore, the effects of different diffusion temperatures on the dark current performance of the devices were researched. The 50% cut-off wavelength of the photodetector is 5.26 μ m at 77 K with 0 V bias. The minimum dark current density is 8.67 × 10 −5 A/cm 2 and the maximum quantum efficiency of 42.5%, and the maximum detectivity reaches 3.90 × 10 10 cm·Hz 1/2 /W at 77 K. The 640 × 512 focal plane arrays (FPA) based on the planner junction were fabricated afterwards. The FPA achieves a noise equivalent temperature difference (NETD) of 539 mK.