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 favorable ruthenium adsorption

model, T1, T4 and H3 special sites were considered. It was found that the most

energetically favorable 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 unfavorable. 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