Dark Count Analysis in 4H-SiC based UV Avalanche Photodiodes with Effective After-pulse Suppression

In this work, based on a series of readout-electronic strategy explorations for the Geiger mode 4H-SiC avalanche photodiodes (APDs), simultaneous low after-pulse rate and preserved single-photon detection efficiency (SPDE) have been achieved, facilitating a comprehensive analysis on the physics origin of the dark counts. The characterizations with a passive quenching circuit indicate an evidently larger dark count rate (DCR) in the SiC APDs based on the ion implantation process. By utilizing a double-gate readout strategy, the after-pulse probability distribution in the time domain has been characterized, featuring a quick drop with time. Meanwhile, gated external bias could effectively reduce the DCR from 35% to 5%, but would sacrifice the SPDE. By developing active quenching circuit with fast quenching and reset components, after-pulse impact has been mostly alleviated with maintained SPDE. This work has then realized the analysis on the DCR characteristics in 4H-SiC APD with well suppressed after pulses, and clarified the point-defect dominated tunneling carrier generation in the dark count, as well as the prior avalanche event dominated after pulse probability distributions in time domain.