Flat epitaxial diamond/Ir(0 0 1) interface visualized by high resolution transmission electron microscopy

High resolution transmission electron microscopy (HRTEM) was used to study the interface structure of epitaxial diamond crystallites deposited on Ir(0 0 1)/SrTiO3(0 0 1). The selected samples did not show any significant surface roughening of the Ir film after the nucleation step. The diamond crystallites formed a flat, sharp, and crystalline interface with the Ir film without any intermediate layer. The epitaxial relationship is diamond (0 0 1)[1 0 0] ∥ Ir(0 0 1)[1 0 0] and the misorientation of the diamond crystallites directly grown on the iridium is smaller than 1°. Homogeneous amorphous interlayers often observed in thick samples are attributed to delamination during cool-down induced by the large thermal misfit between diamond and the substrate. The Ir(0 0 1)/SrTiO3(0 0 1) interface proved to be stable in the harsh CVD plasma environment showing an excellent epitaxy without a measurable misorientation.