Tin deposition on ruthenium (001): a multitechnique surface science study

Abstract

Tin deposition on the Ru(001) surface was studied by Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and low-energy ion scattering spectroscopy (LEISS). Tin deposition (AES signal intensity) versus time plots obtained over the substrate temperature (T[sub s]) range 330-670 K indicate that the Sn adatoms exhibit several different deposition growth modes. At T[sub s] = 330 K the Sn deposition follows a Stranski-Kranstanov growth mode (uniform monolayer followed by three-dimensional growth). Two LEED patterns are seen for T[sub s] = 330 K Sn depositions that are interpreted in terms of ordered Sn overlayers in the submonolayer coverage regime. For Sn depositions at T[sub s] = 500 K the Sn overlayer growth is also approximated by a Stranski-Kranstanov growth mode with the second and subsequent layers exhibiting less three-dimensional nucleation than at 330 K. For specific Sn depositions at T[sub s] > 600 K and upon annealing to 1,000 K, ordered surfaces with ([radical]3[times][radical]3)R30[degrees] and p(2[times]2) LEED patterns are obtained depending upon initial Sn precoverages and annealing temperatures and are suggested to arise from surface alloys. LEISS data indicate that the ([radical]3[times][radical]3)R30[degrees] surface alloy has a surface SnRu atom ratio of 2:1. 30 refs., 8 figs.