Modelling photo-detection efficiency in SiPMs and measuring the quantum yield of silicon: a flexible model from the UV to the IR

We will present an experimentally verified model for characterizing the behavior of Single Photon Avalanche Diodes (SPADs) and silicon photomultipliers (SiPMs). This work has been performed in the context of understanding large-scale, next generation physics experiments utilizing a large number of SiPMs. Measurements have been taken under illumination from the UV to the NIR at various bias voltages, angles of incidence and temperatures. This permits a detailed description of optical transmission into the device, the internal structure, and the probabilities of charge carriers producing an avalanche in different regions of the device. We will also present novel measurements of the so-called ‘quantum yield’ in silicon, the number of electron-hole pairs produced in an Si crystal per photon. This has been measured for high energy photons below 350nm via a novel SiPM based technique. This quantum yield information is incorporated into the framework for relevant photon energies. This model can aid in assessing detector performance across a range of optical inputs, characterize nuisance parameters such as optical cross-talk and inform the design of new devices with higher efficiency.