Radiation effects on Single-Photon Avalanche Diodes manufactured in deep submicron CMOS technology

CMOS Single-Photon Avalanche Diodes (SPADs) have been introduced recently in many scientific applications. This paper reports on the performance, in terms of Dark Count Rate (DCR), of a photo-sensor based on CMOS SPADs. The device has been subjected to an accurate investigation, in order to evaluate its behaviour in a radiation environment. Several irradiation tests were conducted, and a complete survey of their effects on the DCR behaviour has been performed. An overall increase in the DCR level has been measured, meaning that new defects have been introduced in the space charge region of the SPADs. Furthermore, for a fraction of the SPADs, DCR measurements show a Random Telegraph Signal (RTS) temporal pattern.