First fully integrated 2-D array of single-photon detectors in standard CMOS technology

A two-dimensional (2-D) array (4 by 8) of single-photon avalanche diodes integrated in an industrial complementary metal-oxide-semiconductor (CMOS) process is presented. Each pixel combines a photodiode biased above its breakdown voltage in the so-called Geiger mode, a quenching resistor, and a simple comparator. The pitch between the pixels is 75 μm and the diameter of each pixel is 6.4 μm. The full integration allows reducing the number of charge carriers in a Geiger pulse. The electroluminescence responsible for optical crosstalks between pixels is then reduced leading to a negligible optical crosstalk probability. Thanks to the cleanness of the fabrication process, no afterpulsing effects are noticed. At room temperature, most of the pixels exhibit a dark-count rate of about 50 Hz. The detection probability is almost identical for all 32 pixels of the array with relative variation in the range of a few percents. This letter demonstrates the feasibility of an array of single-photon detectors sensitive in the visible part of the spectrum. Besides low production costs and compactness, an undeniable benefit lies in the potential to easily modify the design to fit a specific application. Furthermore, the CMOS integration opens the way to on-chip data processing.