Physics of avalanche diode photodetectors using Particle Monte Carlo simulation

Contacts: Philippe DOLLFUS

Keywords: Single-Photon Avalanche Diode (SPAD), Monte Carlo method, Impact ionization, Avalanche and Quenching, jitter

In this research we investigate all stages of SPAD operation, photon absorption-induced electron-hole pair generation to avalanche triggering and quenching as a function of time by means of self-consistent particle Monte Carlo method to solving the Boltzmann transport equation. This method accounts for all intrinsic sources of stochasticity inherent in charged particle transport, which allows us to describe both avalanche triggering and quenching in terms of probability and jitter.

We also develop a simplified approach of particle Monte Carlo transport based on a real-space Fokker-Planck equation that includes the probabilistic character of impact ionization process. It allows us to consider SPADs of realistic size for direct comparison with experiment.

Such approaches are powerful and very promising to optimally design new generations of this class of Si and Si/Ge photodetectors.

Flagship Projects:

- The GeSPAD project (2020-2024), founded by the Agence Nationale de la Recherche , Ge-based SPADs will be inspected at all possible levels, going from material properties through device physics until circuit optimization. This project will combine advanced characterization techniques on industrial Ge-based prototypes with multi-scale predictive simulation tools from ab initio material calculation to compact modelling of device. The C2N group is focussing on the Monte Carlo investigation of SPAD transient operation and on the full-quantum description the Shockley-Read-Hall generation/recombination rates within the NEGF formalism to consider the impact of trap-assisted tunnelling on the current-voltage characteristics.

- The MODSPADGE project (2024-2027), founded by Bpifrance within the IPCEI program with STMicroelectronics. This project will focus on the Monte Carlo simulation of new-generation Ge and SiGe-based SPAD photodetectors and Ge/Si hybrid architectures. We will develop a state-of-the-art Monte Carlo code dedicated to this type of photodetectors that will enable self-consistent simulation of carrier dynamics in realistically-sized SPADs.

Fundings: