A novel etching solution using molten KOH with Na2O2 additive (KN etching) for dislocation revelation in 4H-SiC epilayers and substrates was proposed. Threading screw and edge dislocations (TSDs and TEDs) were clearly revealed as hexagonal etch pits differing in pit size, and basal plane dislocations (BPDs) as seashell-shaped pits. KN etching has provided a solution to the problem that KOH etching was not effective for dislocation identification in n+-4H-SiC. The influences of SiC off-axis angles, carrier concentrations, and growth techniques on the effectiveness of KN etching have also been investigated. It was shown that KN etching was applicable to SiC epilayers and substrates with any off-axis angle from 0 to 8° and electron concentrations from 1015 to 1019cm-3.

Molten KOH Etching with Na2O2 Additive for Dislocation Revelation in 4H-SiC Epilayers and Substrates. Y.Z.Yao, Y.Ishikawa, Y.Sugawara, H.Saitoh, K.Danno, H.Suzuki, Y.Kawai, N.Shibata: Japanese Journal of Applied Physics, 2011, 50[7], 075502