Anisotropic etching of SiC

The etching effect using molten KOH of micropipes and dislocations in silicon carbide single crystals is investigated. Most of the etch pits become hexagonal due to an anisotropic etching behavior. Micropipes are interconnected with dislocations, and this observation is discussed in relation to the growth process. The hexagonal pattern of micropipes is revealed by rapid etching provided by a large undersaturation. Etching from a melt gives a disintegration of the SiC crystal at the micropipe via spiral dissolution as a consequence of etching near equilibrium conditions. The Si- and C-faces are attacked by molten KOH preferentially and isotropically, respectively The size of the micropipes with increasing etching time is studied for both the Si- and C-faces. The temperature dependence of the etch rate follows an Arrhenius dependence with an apparent activation energy of about 12-15 kcal/mol derived from measuring the etch rate and weight loss. (C) 2000 The Electrochemical Society. S0013-4651(00)02-040-1. All rights reserved.