Hot-Carrier Degradation Modeling of DCR Drift in SPADs

DCR drift (ΔDCR) modeling in Single-Photon Avalanche Diodes (SPADs) is proposed based on hot-carrier degradation (HCD) mechanism. The bond dissociation rate constant is modeled at various stress temperatures and voltages by the carrier energy distribution coupled with the current density considering carriers reaching the mean threshold Si-H bond dissociation energy. The carrier distribution energy was achieved by a Full-Band Monte-Carlo simulation accounting for the band structure and the scattering mechanisms. Hot electrons contributes mostly to the degradation of the top SPAD interface. The carrier density is then extracted from dark- and photo-generated currents together with multiplication current by means of experiment and modeling. ΔDCR is then computed by integrating the carrier generation rate from these stress-induced defects together with the position-dependent breakdown probability. This physic-based compact model allows to predict ΔDCR along stress time under a whole set of characterization and stress conditions.