Micropipes and dislocations in single crystals were revealed by chemical etching. The micropipes were shown to be connected with other structural defects. The Si and C faces were preferentially and isotropically attacked, respectively, by molten KOH. The results were explained with regard to the differing surface free energies of the Si and C faces. The revelation of micropipes was more pronounced on Si faces. The hexagonal patterns of micropipes were revealed by rapid etching, aided by a high undersaturation at the surface. It was shown that etching by a melt led to disintegration of the crystal, at the micropipe, via a spiral dissolution which was due to etching under near-equilibrium conditions. The temperature dependence of the etching rate obeyed an Arrhenius dependence; with an apparent activation energy of some 12 to 15kcal/mol.

Anisotropy of Dissolution and Defect Revealing on SiC Surfaces M.Syväjärvi, R.Yakimova, A.L.Hylén, E.Janzén: Journal of Physics - Condensed Matter, 1999, 11[49], 10041-6