Characterization and Modeling of Breakdown Probability in Sub-Micrometer CMOS SPADs

This paper presents the characterization of two different single-photon avalanche diodes fabricated in a standard 0.15 mu m CMOS process and the modeling of their breakdown probability. The first device is based on a p+/nwell abrupt junction, while the second one has a pwell/n-iso diffused junction. Breakdown voltage and breakdown probability are modeled using both local and dead-space models. While the two models are in agreement for the prediction of breakdown voltage, it is shown that the local model largely underestimates the breakdown probability with respect to experimental results. On the contrary, the voltage and wavelength dependence of breakdown probability can be correctly predicted using the dead-space model.