Enhancing photodetection efficiency of CMOS SiPMs using virtual guard rings in a standard 0.35 µm process

Abstract

Abstract In this letter, a design of virtual guarded SiPMs fabricated in a standard 0.35μm standard complementary metal oxide semiconductor (CMOS) process is introduced. The performance of these virtual guarded cells (VGC) is compared to that of conventional cells with real guard rings, referred to as physical guarded cells (PGC). Specifically, the photon detection efficiency (PDE) of both types of SiPMs is evaluated. For this, PDE calculations are conducted at different overvoltages (OVs) and the PDE is compared depending on the wavelength before conducting measurements. The results demonstrate that the VGC SiPM outperforms the PGC SiPM, exhibiting a true PDE of (22.5 ± 0.5)%, which is significantly higher than the PDE of (10.9 ± 0.3)% obtained for the PGC SiPM. The superior PDE of the VGC SiPM is attributed to a larger active or photosensitive area due to the virtual guard rings and a thinner n‐layer in the photosensitive region.

Keywords

• avalanche diodes
• CMOS image sensors
• photon counting