Growth and surface alloy formation of Mg on Ag(100)

X-ray induced photoemission (XPS and XAES) and low energy electron diffraction have been used to study growth mechanisms and reaction of Mg with the Ag(100) surface. At adsorption temperatures below 200 K layer-by-layer growth has been found, which is transformed into a Stranski-Krastanov growth mode at a surface temperature of 300 K. In the submonolayer regime a well ordered c(2 X 2) LEED pattern is observed at a coverage of 0.5 monolayers (ML). Both LEED and XPS reveal a morphological transition from the pseudomorphically grown monolayer to the Mg hcp structure for thicker layers. These layers are stable at surface temperatures below 300 K. Above this temperature desorption sets in and finally at 420 K a Mg concentration equivalent to 0.5 ML remains, which forms a disordered Mg-Ag alloy with the topmost silver layer(s), as concluded from XAES. This alloy is stable to at least 750 K. (C) 1999 Elsevier Science B.V. All rights reserved.