Accurate Prediction of Photon Detection Probability Based on the 2-D Dead-Space Model for SPADs

In this article, we propose an accurate procedure for predicting the photon detection probability (PDP) for single-photon avalanche diodes (SPADs). The energy threshold needed for triggering impact ionization, that is, the dead space, was carefully considered and developed into a 2-D solution. The input parameters are based on the manufacturing process and device layout. The breakdown probability of each point on the 2-D profile was calculated without adding fitting parameters, which can overcome the inaccurate prediction caused by the uneven distribution of the electric field and photon generation for the device with the guard ring. Two sets of SPADs based on 180 nm for front-side illumination and 55 nm for back-side illumination were fabricated and tested. The simulation and experimental results are in accordance with each other. This procedure makes it very easy to optimize the device structure based on the simulation results. In addition, the invention can invoke graphics processing units (GPUs) in the MATLAB platform to perform parallel acceleration calculations and improve the calculation efficiency.