In recent years, Single-Photon Avalanche Diodes (SPADs) have gained significant relevance in applications requiring the detection of weak or single-photon optical signals with high temporal resolution. Thanks to their ability to convert the absorption of a single photon into a macroscopic electrical current, they are widely used in photon counting, time-resolved imaging, LiDAR systems, fluorescence measurements, and other advanced sensing applications. Unlike conventional photodiodes SPADs operate in Geiger mode, where a single carrier triggers a self-sustaining avalanche process. As a consequence, the device behaves as a digital detector, producing a current pulse associated with a detection event. However, operation above breakdown also introduces critical modeling challenges.