Fabrication of epitaxial diamond thin film on iridium

We have successfully grown smooth diamond thin films epitaxially on (001) iridium surfaces through a direct-current plasma chemical vapor deposition process with two steps: ion irradiation pretreatment and diamond growth. The epitaxial areas of diamond thin films with a mean thickness of about 1.5 μm seem to act as optical mirrors. The average roughness (Ra) of the thin film, as measured by atomic force microscopy, is about 1 nm. Confocal Raman spectroscopy was used to investigate the depth profile of the thin film. Raman bands due to nondiamond carbon components were nominal at the diamond/iridium interface or at other depths.