Comparative columnar porous etching studies on n-type 6H SiC crystalline faces

Comparative photo‐electrochemical etchings have been performed on the Si‐face, C‐face and a‐face of n‐type 6H SiC. Two kinds of columnar pores are developed: nano‐columnar (∼20 nm diameter) and macro‐columnar (∼one µm diameter). The time dependences of the current densities during the etchings are discussed. Our results show that the nano‐columnar pore formation is associated with the anisotropic electrochemical oxidation reaction rate on the different crystal faces. Our experiments show that, in the case of 6H SiC, the C‐face should be used for nano‐columnar pore formation. The electrochemical oxidation rate increases with the surface C atom density of SiC. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)