Influence of Guard-Ring Structure on the Dark Count Rates of Silicon Photomultipliers

We present the diverse characteristics of silicon photomultipliers using three different structures. Three different trench gap-filled materials are fabricated, and a detailed comparative analysis on their device performances is carried out. The high energy resolution in the gamma spectrum (16%-17%), and the highest fill factor (73.6%) are achieved with the trench-type guard-ring structure. However, due to its trench-associated defects, the trench-type guard-ring structure showed the lowest dark count rate characteristic in the single microcell, which dramatically slowed due to the decreased probability of crosstalk in the 4 × 4 matrix array Si photomultipliers. In particular, the performance of the oxide + polysilicon gap-filled trench-type guard-ring structure is intermediate in most aspects of the performance compared to the other types of guard-ring structures.