After-Pulse Characterizations of Geiger-Mode 4H-SiC Avalanche Photodiodes

In this work, the after-pulse properties of 4H-SiC ultraviolet (UV) avalanche photodiodes (APDs) working in gated quenching mode are firstly characterized by using a double gate method. The after-pulse probability is determined as a function of delay time at various overbias voltages and temperatures. It is found that the after-pulse probability of 4H-SiC APDs would decrease at higher chip temperature, supporting the carrier trapping/releasing mechanism. Compared to state-of-the-art Geiger-mode Si APDs, the 4H-SiC APD exhibits considerably larger after-pulsing effect, which should be mainly caused by high density point defects within the SiC epilayer. The maximum signal repetition rate of the SiC APD in gated quenching operation mode is estimated, which is a key performance parameter for future UV laser radar and quantum communication applications.