Passive quenching, signal shapes, and space charge effects in SPADs and SiPMs

TL;DR

This paper models the dynamics of passive quenching in single-photon avalanche diodes and SiPMs, deriving signal shapes and analyzing space charge effects through a microscopic and circuit-based approach.

Contribution

It provides a microscopic model combining avalanche dynamics with circuit elements, including space charge effects, to predict signal shapes in SPADs and SiPMs.

Findings

Signal shape expressions derived for simple electric fields

Numerical methods for realistic device geometries

Space charge effects distort signals but do not change quenching mechanisms

Abstract

In this report we study the dynamics of passive quenching in a single-photon avalanche diode. Our discussion is based on a microscopic description of the electron-hole avalanche coupled to the equivalent circuit of the device, consisting of the quench resistor and the junction capacitance. Analytic expressions for the resulting signal shape are derived from this model for simple electric field configurations, and efficient numerical prescriptions are given for realistic device geometries. Space charge effects arising from the avalanche are included using simulations. They are shown to distort the signal shape, but alter neither its basic characteristics nor the underlying quenching mechanism.