Low dark current lateral Ge PIN photodetector array with resonant cavity effect for short wave infrared imaging

High-performance germanium (Ge) lateral PIN photodetector (PD) arrays for short wave infrared (SWIR) imaging based on Ge-on-insulator (GOI) platform was proposed and demonstrated. The high-quality GOI platform with top-Ge layer thickness of 1.25 μ m and threading dislocation density of less than 10 5 cm −2 was prepared by using bonding and smart-cut technology. P -type and N -type regions with centrosymmetric racetrack shapes were introduced to lower the sidewall electric field and suppress the surface leakage current of the PD. Benefiting from the high-quality of the GOI platform and the unique design of lateral active regions, a low dark current of 2 nA under −1 V with outstanding rectification ratio of 2.1 × 10 6 were obtained at room temperature. Through constructing a vertical resonant cavity by SiO 2 passivation layer and the Si/SiO 2 substrate, the responsivity at 1550 nm was enhanced to 0.46 A W −1 with a high specific detectivity of 3.09 × 10 10 cm·Hz 1/2 ·W −1 under −1 V. Ultimately, SWIR imaging was demonstrated by a Ge lateral PIN PD line array with 1 × 8 pixels under zero bias at room temperature. The results indicate that the proposed lateral Ge PD structure holds great application potential in the field of SWIR imaging.