Optical and Electrical Characterization of Single-Photon Avalanche Diodes Fabricated in CMOS Technology

This paper presents the design, fabrication, and characterization of single-photon avalanche diodes (SPADs) fabricated in 110 nm CMOS technology, optimized for photon-counting imaging and LiDAR applications. The SPADs are designed with active region sizes of $5 \mu ~\mathrm{m}, 10 \mu ~\mathrm{m}, 15 \mu ~\mathrm{m}$, and 20 $\mu \mathrm{m}$, and feature a retrograde virtual guard-ring (GR) structure to prevent premature edge breakdown. Electrical and optical characteristics, including current-voltage (I-V) curve, dark count rate (DCR), and photon detection probability (PDP), were measured to evaluate the performance of SPADs.

I. Introduction

Single-photon avalanche diodes (SPADs) have emerged as a pivotal technology in photon-counting applications due to their extraordinary sensitivity, enabling the detection of single photons with nanosecond timing resolution. As advancements in low-light detection are crucial in diverse fields, SPAD-based sensors have gained significant traction, particularly in photon-counting image sensors and light detection and ranging (LiDAR) systems. These applications leverage the unique characteristics of SPADs to push the boundaries of sensing accuracy, speed, and resolution, making them indispensable in modern imaging and ranging technologies [1]–[5].