A MISFIT-INDUCED RELAXATION STRUCTURE OF EPITAXIAL CU FILMS ON RU(0001) AND ITS POTENTIAL USE FOR NANOSTRUCTURING

For Cu films on Ru(0001) and deposition temperatures around 400 K, a m etastable quasi-hexagonal relaxation structure (unit mesh similar to 5 0 Angstrom) was observed by means of scanning tunneling microscopy. Th e structure appears at film thicknesses above three monolayers and for ms during the relief of misfit-induced strain. It can be considered as a preformation of the stable moire-like relaxation structure found at temperatures above 600 K. Energetically unfavourable on-top positions of the Cu atoms are avoided by the formation of triangular domains wh ere the atoms mainly occupy face-centred cubic hollow sites. For O-med iated Cu film growth where an O/Cu surfactant structure floats on-top the Cu film, we demonstrate that the domains act as traps for Cu adato ms, allowing to prepare regular patterns of triangular Cu islands almo st homogeneous in size. (C) 1998 Elsevier Science B.V. All rights rese rved.