A frontside-illuminated single-photon avalanche diode with high photon detection probability

Abstract

A frontside-illuminated single photon avalanche diode based on 110 nm CMOS process is proposed in this paper. The P-well/Deep N well multiplication junction is adopted to enhance the near infrared absorption. To reduce the dark count rate, only the well guard ring is used in the photosensitive region to avoid the defects caused by shallow trench isolation process. The SPAD achieves a DCR of 3.2 cps/μm2 at room temperature, a peak photon detection probability over 40% at 500 nm, and over 3.6% at 905 nm with 2.0 V excess bias voltage. The device we designed is very suitable for LiDAR applications.