Structure and surface morphology of epitaxial Ni films grown on MgO(111) substrates:: growth of high quality single domain films

Ni films were deposited by using ultra high vacuum DC magnetron sputtering onto MgO(1 1 1) substrates kept at temperatures between 20 degrees C and 600 degrees 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 degrees C the Ni 1 1 1 rocking curve width is similar to 0.25 degrees, 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 less than or equal to 200 degrees C and at 600 degrees C, while at 300 and 400 degrees 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 degrees C and a local minimum at 300 degrees 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. (C) 1999 Published by Elsevier Science B.V. All rights reserved.