SPAD Figures of Merit for Photon Counting, Photon Timing, and Imaging Applications: A Review
Single photon avalanche diodes (SPADs) emerged as the most suitable photodetectors for both single photon counting and photon timing applications. Different complementary metal oxide semiconductor (CMOS) devices have been reported in the literature, with quite different performance and some excelling in just few of them, but often at different operating conditions. In order to provide proper criteria for performance assessment, we present some figures of merit (FoMs) able to summarize the typical SPAD performance (i.e. photon detection efficiency, dark counting rate, afterpulsing probability, hold off time, and timing jitter) and to identify a proper metric for SPAD comparisons, when used either as single pixel detectors or in imaging arrays. The ultimate goal is not to define a ranking list of best in class detectors, but to quantitatively help the end user to state the overall performance of different SPADs in either photon counting, timing, or imaging applications. We review many CMOS SPADs from different research groups and companies, we compute the proposed FoMs for all them and, eventually, we provide an insight on present CMOS SPAD technologies and future trends.
IEEE Sensors Journal