Etching Kinetics of α-SiC Single Crystals by Molten KOH

Abstract

The etching behaviour of {alpha}-SiC single crystals by molten KOH has been investigated. The etching rate is significantly affected by the etching ambience: dry air yields an etching rate eight times larger than nitrogen. This result suggests an essential role of dissolved oxygen in the melt for the molten KOH etching of SiC. The {l_brace}0001{r_brace} surface shows a surface polarity dependence: the etching rate of (000 anti 1)C is about four times larger than that of (0001)Si. The etching rate of (000 anti 1)C exhibits an Arrhenius type temperature dependence with an activation energy of 15-20 kcal/mol. The obtained activation energy and selectivity between (000 anti 1)C and (0001)Si are quite similar to those for thermal oxidation. The carrier concentration hardly influences the etching rate up to 3 x 10{sup 19}cm{sup -3}, while crystal with a larger hexagonality shows a larger etching rate. (orig.) 12 refs.