Influence of Defects in 4H-SiC Avalanche Photodiodes on Geiger-Mode Dark Count Probability

4H-SiC single photon avalanche diodes are reported. A separate absorption and multiplication non-reach through device structure was optimized for operation in Geiger mode. An estimated dark current at a gain of 1000 was ranging between 0.4 pA (0.75 nA/cm2) and 20nA (38 A/cm2) on devices with an effective mesa diameter of 260 m. The electron beam induced current technique was used to image defects in the active region of studied devices. Increased reverse bias leakage current and increased Geiger mode dark count probability were correlated with the presence of large number of defects. Single photon detection efficiencies of up to 11% were measured at a wavelength of 266 nm in Geiger mode.