Local initial heteroepitaxial growth of diamond (111) on Ru (0001)/c-sapphire by antenna-edge-type microwave plasma chemical vapor deposition

Heteroepitaxial growth is critical for large-scale synthesis of diamond (111) substrates. In this study, the local initial epitaxial growth of diamond (111) on Ru/c-sapphire was investigated. As the economic viability of ruthenium (Ru) is more than that of iridium (Ir), a 150-nm Ru (0001) thin film was sputter-deposited on an Al2O3 (0001) substrate using a RF/DC magnetron sputtering system. X-ray diffraction analyses of the Ru film revealed the (0001) phase orientation with high crystalline quality. Both bias-enhanced nucleation and initial heteroepitaxial growth of diamond were realized via antenna-edge-type microwave plasma chemical vapor deposition. After 30 min of heteroepitaxial growth, the crystallite (diameter ∼500 nm) with a smooth surface was observed through scanning electron microscopy. Electron backscattering diffraction (EBSD) orientation mapping indicated the presence of the highly oriented diamond (111) crystallite. The epitaxial orientations between diamond (111) and Ru were determined as [111]diamond//[0001]Ru and [112¯]diamond//[101¯0]Ru. The EBSD pole-figure pattern represented the formation of a double positioning defect. This study demonstrated the feasibility of heteroepitaxial growth of diamond (111) on Ru, which provides a more economically viable approach to fabricating large-size diamond substrates.