Analysis of surface morphology at leakage current sources of 4H–SiC Schottky barrier diodes

The surface morphologies of leakage current sources of 4H–SiC Schottky barrier diode were analyzed using atomic force microscopy (AFM). Nanosized circular cone shaped pits (nanopits) were observed at the leakage current sources. Leakage currents were generated due to the concentration of electric fields at the nanopits during measurements of the reverse bias characteristics. The positions of the nanopits correspond to the positions of threading dislocations (TDs), which were identified from molten potassium hydroxide (KOH) etching. The most important factor of leakage current generation was determined to be the surface morphology of the TDs rather than the presence of TDs.