Effect of a Single Threading Dislocation on Electrical and Single Photon Detection Characteristics of 4H-SiC Ultraviolet Avalanche Photodiodes

We fabricated 4H-SiC ultraviolet avalanche photodiode (APD) arrays and systematically investigated the effect of threading dislocations on electrical and single photon detection characteristics of 4H-SiC APDs. Based on a statistical correlation study of individual device performance and structural defect mapping revealed by molten KOH etching, it is determined with high confidence level that even a single threading dislocation within APD active region would lead to apparent device performance degradation, including increase of dark current near breakdown voltage, premature breakdown and reduction of single photon detection efficiency at fixed dark count rate.