Mg deposition on Ag(1 0 0): temperature evolution of the structural and electronic properties R. Moroni, F. Bisio, L. Mattera * Unita ` INFM di Genova, Dipartimento di Fisica dell’Universita ` di Genova, IMEM-CNR Sezione di Genova, Via Dodecaneso 33, I-16146 Genova, Italy Abstract Structural and electronic properties of ultrathin Mg films on Ag(1 0 0) have been investigated by means of metastable de- excitation spectroscopy (MDS), work function change (Df), electron diffraction and helium reflectivity (R He ) measurements. At room temperature Mg grows on Ag(1 0 0) following the Stranski–Krastanov growth mode. Successive annealing of a 10 ML thick Mg film leads to its almost complete desorption at about 390 K and to the formation of a Mg–Ag alloy. R He and electron diffraction measurements indicate that for annealing temperatures between 480 and 570 K, the alloy orders with a cð2  2Þ periodicity. Further annealing at higher temperatures restores the initial Ag(1 0 0) surface. # 2003 Elsevier Science B.V. All rights reserved. PACS: 68.55.-a; 68.49.Jk; 71.20.Be; 82.80.Pv Keywords: Magnesium; Silver; Alloy 1. Introduction Oxide thin films have recently attracted a great interest in the surface science community. Such an interest is motivated by the technological and funda- mental relevance of oxide and ceramic surfaces [1]. Due to the oxidising properties of the terrestrial environment, a thin native oxide film commonly cov- ers the vast majority of metals and governs their surface properties. Besides the practical interest in native oxide films, great attention has been paid to the epitaxial growth of thin film oxides on metallic substrates as physical properties of oxide/metal systems may differ consider- ably from those of bulk oxides. In particular, reduced dimensionality and hybridizational effects at the metal/ oxide interface may strongly modify the electronic properties of oxide ultrathin films. The growth of thin film oxides on a metal substrate may make available high quality oxide surfaces. Furthermore, despite the insulating nature of many oxide materials, the growth of thin film on a conducting substrate may lead to con- ducting thin film oxides which can be then investigated by means of charged-particle spectroscopic, diffractive and imaging techniques. One of the first and most investigated oxide/metal systems is MgO/Ag(1 0 0). Thanks to the low lattice mismatch, it is possible to obtain MgO thin films with single crystalline quality by evaporating Mg on Ag(1 0 0) in a background oxygen pressure while Applied Surface Science 212–213 (2003) 224–229 * Corresponding author. Tel.: þ39-0103536287; fax: þ39-010311066. E-mail address: mattera@fisica.unige.it (L. Mattera). URL: http://server1.fisica.unige.it/surfmag 0169-4332/03/$ – see front matter # 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0169-4332(03)00092-8