Epitaxial (111) Films of Cu, Ni, and CuxNiy on α–Al2O3(0001) for graphene growth by chemical vapor deposition

Published

September 21, 2012

Author(s)

David L. Miller, Mark W. Keller, Justin Shaw, Ann Chiaramonti Debay, Robert Keller

Abstract

Films of (111)-textured Cu, Ni, and Cu_xNi_y 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 [110]_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 Cu_xNi_y 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.

Citation

Journal of Applied Physics

Volume

112

Pub Type

Journals

Keywords

epitaxy, reactive sputtering, graphene, grain boundaries, single crystal

Citation

Miller, D. , Keller, M. , Shaw, J. , Chiaramonti Debay, A. and Keller, R. (2012), Epitaxial (111) Films of Cu, Ni, and Cu_xNi_y on α–Al₂O₃(0001) for graphene growth by chemical vapor deposition, Journal of Applied Physics (Accessed November 8, 2024)