Structure and surface morphology of epitaxial Ni films grown on MgO(1 1 1) substrates: growth of high quality single domain films

• Published in: Journal of crystal growth 1999-03, Vol.197 (4), p.849-857
• Main Authors: Sandström, Per, Svedberg, Erik B, Birch, Jens, Sundgren, Jan-Eric
• Format: Article
• Language: English
• Subjects: Applied sciences; Atomic force microscopy; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Epitaxial growth; Exact sciences and technology; Magnesium oxide; Materials science; Metals. Metallurgy; Methods of deposition of films and coatings; film growth and epitaxy; Nickel; Physics; Solid surfaces and solid-solid interfaces; Structure and morphology; thickness; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Thin films; X-ray diffraction
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/S0022-0248(98)00972-5

Ni films were deposited by using ultra high vacuum DC magnetron sputtering onto MgO(1 1 1) substrates kept at temperatures between 20°C and 600°C. The structure and the surface morphology of the 100 nm thick films were analyzed using X-ray diffraction (XRD), atomic force microscopy and Auger electron spectroscopy. XRD analysis shows that all Ni films have a strong 〈1 1 1〉 oriented texture with high out-of-plane as well as high in-plane orientations with an increased crystalline quality with temperature. At 300°C the Ni 1 1 1 rocking curve width is ∼0.25°, showing a high crystalline quality for a heteroepitaxial metal film. Pole-figure analysis shows that the films are built up of two domains for temperatures ⩽200°C and at 600°C, while at 300 and 400°C only a single domain is formed. The root mean square surface roughness of the films increases with temperature with a local maximum between 150 and 200°C and a local minimum at 300°C, corresponding to the transition from two domains to one. The mechanism behind the high in-plane orientation, despite the large lattice misfit between Ni and MgO, based on super cell matching is discussed. Possible mechanisms for the transition from two domains to one are also discussed.