Epitaxial (111) Films of Cu, Ni, and CuxNiy on α–Al2O3(0001) for graphene growth by chemical vapor deposition
David L. Miller, Mark W. Keller, Justin Shaw, Ann Chiaramonti Debay, Robert Keller
Films of (111)-textured Cu, Ni, and CuxNiy were evaluated as substrates for chemical vapor deposition of graphene. A metal thickness of 400 nm to 700 nm was sputtered onto a substrate of α–Al2O3(0001) at temperatures of T=250°C to 650°C. X-ray and electron backscatter diffraction measurements showed all films have pure (111) texture but have grains with in-plane orientations differing by 60°. The in-plane epitaxial relationship for all films was metal||[10\bar1}0]Ald2^O3^. Reactive sputtering of Al in O2 before metal deposition resulted in a single in-plane orientation over 97percent} of the Ni film but had no significant effect on the Cu grain structure. Transmission electron microscopy showed a clean Ni/Al2O3 interface, confirmed the epitaxial relationship, and showed that formation of the 60° twin grains was associated with features on the Al2O3 surface. Increasing total pressure and Cu vapor pressure during annealing decreased the roughness of Cu and and CuxNiy films. Graphene grown on the Ni(111) films was more uniform than that grown on polycrystalline Ni/SiO2 films, but still showed thickness variations on a much smaller length scale than the distance between grains.
Journal of Applied Physics
epitaxy, reactive sputtering, graphene, grain boundaries, single crystal
, Keller, M.
, Shaw, J.
, Chiaramonti Debay, A.
and Keller, R.
Epitaxial (111) Films of Cu, Ni, and Cu<sub>x</sub>Ni<sub>y</sub> on α–Al<sub>2</sub>O<sub>3</sub>(0001) for graphene growth by chemical vapor deposition, Journal of Applied Physics
(Accessed December 9, 2023)