A study was made of the nano-patterning of CoO film induced by misfit dislocation networks at the interface with a Ag(001) substrate. Grazing incidence diffraction, X-ray photo-emission spectroscopy and low-energy electron diffraction were used to characterize the chemistry and structure of the CoO layers. The X-ray photo-electron spectrum of the Co 2p core level permitted the establishment of the stoichiometric growth of CoO. The structure of the CoO film together with the absorption sites of cobalt and O atoms was determined, thanks to grazing incidence diffraction measurements. The evolution of the in-plane lattice constant of the CoO was monitored as a function of the film thickness. It turned out that the CoO film growth began with the same in-plane lattice constant of the Ag(001) substrate up to 3 to 4 monolayers. The in-plane parameter of CoO then steadily increased before reaching a stable value of 2.98Å at 23ML. During the relaxation process, at about 8ML of film thickness, the formation of a buried misfit dislocation network was observed. These dislocations, that had a period of 9.2nm for a film thickness of 23ML, induced mosaicity in the CoO film; which then appeared as a regular distribution of tilted domains.

Nano-Structuration of CoO Film by Misfit Dislocations. P.Torelli, E.A.Soares, G.Renaud, S.Valeri, X.X.Guo, P.Luches: Surface Science, 2007, 601[13], 2651-5