A deep-junction single-photon detector with field polysilicon gate structure for increased photon detection efficiency and reduced dark count noise

Abstract A high-sensitivity, low-noise single photon avalanche diode (SPAD) detector was presented based on a 180 nm BCD process. The proposed device utilizes a p-implant layer/high-voltage n-well (HVNW) junction to form a deep avalanche multiplication region for near-infrared (NIR) sensitivity enhancement. By optimizing the device size and electric field of the guard ring, the fill factor (FF) is significantly improved, further increasing photon detection efficiency (PDE). To solve the dark noise caused by the increasing active diameter, a field polysilicon gate structure connected to the p+ anode was investigated, effectively suppressing dark count noise by 76.6%. It is experimentally shown that when the active diameter increases from 5 to 10 μ m, the FF is significantly improved from 20.7% to 39.1%, and thus the peak PDE also rises from 13.3% to 25.8%. At an excess bias voltage of 5 V, a NIR photon detection probability (PDP) of 6.8% at 905 nm, a dark count rate (DCR) of 2.12 cps/ μ m 2 , an afterpulsing probability (AP) of 1.2%, and a timing jitter of 216 ps are achieved, demonstrating excellent single photon detection performance.