[Zurück]

C. Eisenmenger-Sittner, E. Klein, B. Schwarz, C. Tomastik, P.B. Barna, A. Kovács:
"SOLID STATE SURFACE WETTING OF TIN ON ALUMINIUM UNDER UHV CONDITIONS";
Vortrag: Joint Vacuum Conference 10, JVC-10, Portoroz, Slovenien; 28.09.2004 - 02.10.2004.

If Tin (Sn)-islands exist on a bare Aluminium (Al)-surface, Sn forms a monoatomic wetting layer on Al under Ultra High Vacuum (UHV) conditions. The islands act as Sn-reservoirs and emit Sn until a monolayer of Sn is formed on the surface. Experimentally this process was investigated by Scanning Auger Microscopy (SAM). The over-all thermodynamic driving force is the reduction of the surface energy of the bare Al-layer by the total coverage with Sn.
In this paper the mechanisms leading to wetting layer formation will be discussed in more detail by means of thermodynamic considerations and Kinetic Monte Carlo Simulations (KMC). Thermodynamics is employed to describe the lateral coverage of the free Al surface by mass emission from pre-existing Sn-islands. The Surface energy of the bare surface is considered higher than the surface energy of the totally covered system. KMC, on the other hand, will be employed to describe the dynamics of the process and to understand the fact why the thickness of the wetting layer is limited to one monolayer. From a comparison with experimental data from SAM measurements the microscopic diffusion parameters which are involved in the formation of the wetting layer are qualitatively identified.

The work was supported by the Austrian Science Fund under Grant P-15739-N02. The Authors also wish to acknowledge the financial support of the Austrian-Hungarian Intergovernmental Program TeT under contract no.A-23/02 for investigations related to this work.