Effects of Surface and Crystalline Defects on Reverse Characteristics of 4H-SiC Junction Barrier Schottky Diodes

To clarify the relationship between the dispersed reverse characteristics of 4H-SiC junction barrier Schottky (JBS) diodes and defects, we investigated the sensitivity of the reverse characteristics to surface and crystalline defects in 4H-SiC epitaxial layers. Strong correlations were obtained between the reverse characteristics of 4H-SiC JBS diodes and surface defects. Micropipes or particles reduced blocking voltage and carrot defects increased leakage current. Furthermore, the leakage current of 4H-SiC JBS diodes depends on the etch pit density of threading dislocations (TDs). Etch pits formed from TDs increased leakage current by about 10-9 A in samples without surface defects. In addition, hexagonal etch pits formed from unusual crystalline defects were observed; they also increased leakage current.