Ordered structures of tin-adsorbed Cu(0 0 1) surfaces with over monolayer coverage

Surface structures of tin (Sn) adsorbed Cu(0 0 1) have been studied by scanning tunneling microscopy (STM), low energy electron diffraction (LEED), and Sn 4d core-level spectroscopy. A structural model for the 5 8 mono-atomic-layer (ML) Sn-adsorbed Cu(0 0 1) surface is proposed on the basis of the observed atomic images and the core-level spectrum. The model is consistent with a height profile of the phase boundary between 1 2 ML Sn on Cu(0 0 1) and 5 8 ML Sn on Cu(0 0 1). After annealing to 410 K, the surface structure of 5 8 ML Sn on Cu(0 0 1) changed to a mixture of 1 2 ML Sn on Cu(0 0 1) areas and a new phase, which has a Sn coverage of about 2 ML. From the STM observation, the surface of the new phase consists of 4 3 - 3 4 domains separated by a disordered area. We propose a structure model consistent with the observed results.