Orientation Dependent Structural Facet Recognition Method in Anisotropic Wet Etching on R-plane Single Crystal Sapphire

Considering the special effect of patterned r-plane sapphire substrate for the growth of nonpolar GaN, a model is proposed by introducing a modified Wulff- Joccodine method to identify the topography of structural facets. The r-plane sapphire etching field is obtained by rotating the c-plane sapphire etch rate hemisphere, resulting in different structural characteristics. The proposed model provides a reliable prediction of microstructure topography by key orientations etched on r-plane sapphire and explains their morphological evolution process.