First-principles calculations were used to analyze ruthenium adsorption and diffusion on GaN(00•1) surfaces in a 2x2 geometry. The calculations were performed using the generalized gradient approximation, with ultra-soft pseudopotential, within density functional theory. The surface was modelled by using the repeated-slabs approach. In order to study the most favourable ruthenium adsorption model, T1, T4 and H3 special sites were considered. It was found that the most energetically favourable structure corresponded to the Ru- T4 model or the ruthenium adatom located at the T4 site, while ruthenium adsorption on top of a gallium atom (T1 position) was totally unfavourable. Ruthenium diffusion on the surface encountered an energy barrier of 0.612eV. The resultant reconstruction of ruthenium adsorption on the GaN(00•1)-(2x2) surface presented a lateral relaxation of some hundredth of an Å in the most stable site.

Ruthenium Adsorption and Diffusion on the GaN(0001) Surface. C.O.López, W.L.Pérez, J.A.Rodríguez: Applied Surface Science, 2009, 255[6], 3837-42