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 mu m and threading dislocation density of less than 105 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 x 106 were obtained at room temperature. Through constructing a vertical resonant cavity by SiO2 passivation layer and the Si/SiO2 substrate, the responsivity at 1550 nm was enhanced to 0.46 A W-1 with a high specific detectivity of 3.09 x 1010cm center dot Hz1/2 center dot W-1 under -1 V. Ultimately, SWIR imaging was demonstrated by a Ge lateral PIN PD line array with 1 x 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.