The Effect of a Deep Virtual Guard Ring on the Device Characteristics of Silicon Single Photon Avalanche Diodes

Silicon single-photon avalanche diodes (Si-SPADs) fabricated with standard CMOS technology and providing the advantages of low noise, low cost, and compatibility with additional circuits are promising candidates for single-photon detection fields. The guard ring is a key component of SPADs, which prevents premature edge breakdown and improves the electric field distribution to the intended multiplication region. The choice of proper physical dimensions, especially the active radius (AR) and the size of the guard ring, is important for the better performance of Si-SPADs. In this paper, a Si-SPAD with a deep virtual guard ring fabricated through deep well diffusion is proposed and the effect of the physical variation of the AR and guard ring width on the device characteristics is investigated. In addition, the effect of physical variation on the device characteristics is analyzed and explained by means of technology computer-aided design (TCAD) simulations.