First-principles calculations were used to analyze ruthenium adsorption and diffusion on the GaN(00•1) surface 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 using the repeated slabs approach. 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 the ruthenium adsorption on top of a gallium atom (T1 position) was totally unfavourable. The ruthenium diffusion on the surface revealed an energy barrier of 0.612eV. The resultant reconstruction of the ruthenium adsorption on the GaN(00•1)-2x2 surface presented a lateral relaxation of some one-hundredth of an Ångstrom unit 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