Dislocation Revelation in Highly Doped N-Type 4H-SiC by Molten KOH Etching with Na2O2 Additive
We have proposed a new wet etching recipe using molten KOH and Na2O2 as the etchant (“KN etching”) for dislocation revelation in highly doped n-type 4H-SiC (n+-4H-SiC). Threading screw dislocations (TSDs) and threading edge dislocations (TEDs) have been clearly revealed as hexagonal etch pits differing in pit sizes, and basal plane dislocations (BPDs) as seashell-shaped pits. This new etching recipe has provided a solution to the problem that conventional KOH etching is not effective for dislocation identification in 4H-SiC if the electron concentration is high (>mid-1018 cm-3). We have investigated the effect of SiC off-cut angle on KN etching and it has been shown that the “KN etching” is applicable for the n+-SiC substrate with off-angle from 0o to 8o.
Edouard V. Monakhov, Tamás Hornos and Bengt. G. Svensson
Y. Z. Yao et al., "Dislocation Revelation in Highly Doped N-Type 4H-SiC by Molten KOH Etching with Na2O2 Additive", Materials Science Forum, Vols. 679-680, pp. 290-293, 2011