RTS fluctuations in the DCR of 150 nm CMOS SPADs before and after exposure to neutrons

Random telegraph signal-like fluctuations are investigated in single photon avalanche diodes (SPADs) fabricated in a 150~nm CMOS technology before irradiation and after exposure to neutrons up to a maximum final fluence of about 4.3x10
¹⁰
1 MeV equivalent neutrons cm
^-2
. The devices under test (DUTs) consist of two arrays of sensors, belonging to the same chip, with different active area and based on a passive quenching architecture. Pre-screening of the DUTs in search for RTS behavior is performed based on low time resolution measurements by means of a machine learning algorithm, trained with data from previous measurements. DCR measurements performed with much higher time resolution at different temperatures are used to investigate the activation energy of the defects, both those already present in the device before irradiation and those induced by neutrons, at the origin of the RTS behavior.