Comparator-based measurement scheme for dark-count rates in single photon avalanche diodes

III-V single photon avalanche diode (SPAD) sensitivity at wavelengths > 1 μm typically comes at the expense of higher dark-count rates and afterpulsing compared to silicon SPADs. Regarding the measurement of dark-count rates, conventional counters are limited by the deadtime required to quell afterpulsing effects; this led to the adoption of time-correlated single photon counting (TCSPC). In this paper, a technique for measuring the dark-count rates encountered in III-V SPADs using only a comparator and an averaging oscilloscope is reported. A detailed explanation of the technique is presented along with a semianalytical proof, simulation results comparing the technique´s validity in comparison to TCSPC, and example measurements.