Rotational Honeycomb Epitaxy of Ru Thin Films on Sapphire (0001) Substrate

Abstract

Rotational honeycomb epitaxy of hexagonal Ru films was achieved on c-plane sapphire substrates by pulsed laser ablation with the a-axis ratio of √3. The crystal structure and crystallinity of the Ru films were examined by X-ray diffraction and pole figure measurements, respectively. The Ru films were found to be epitaxially grown with an a-axis rotation by 30° around the a-axis of sapphire, resulting in the crystallographic relationship of (0001)Ru // (0001) sapphire and <110 > Ru // <100 > sapphire. This is because the lattice mismatch between <110 >Ru and <100 > sapphire is as small as about 1.3%.