Ab-initio studies of the adsorption of a B ad-atom on GaN surfaces

作者：Palomino Rojas L; Garcia Diaz Reyes; Cocoletzi Gregorio H^*; Takeuchi Noboru

来源：Journal of Crystal Growth, 2012, 338(1): 62-68.

DOI：10.1016/j.jcrysgro.2011.07.037

• Adsorption
• Surface structure
• Nitrides
• Semiconducting materials

The energetics and the structural properties of a B ad-atom adsorbed on the GaN (0001) and GaN(000 (1) over bar) surfaces have been investigated using ab-initio total energy calculations. In all cases, the boron ad-atom does not want to occupy positions above Ga atoms, but it prefers to replace a top layer Ga atom. In an ideally GaN (0001) bulk terminated surface, and when the B atom is constrained to remain on top of the surface, the T4 site configuration is the most favorable. However a structure in which the B atom replaces a Ga atom of the first monolayer and the Ga atom occupy a H3-2 site has the lowest energy, and therefore it is the ground state. The GaN (0001) pseudo-(1 x 1) surface have been modeled with root 3 x root 3-R30 degrees unit cell with 4 Ga atoms on the top layer. In the most stable configuration, the boron atom substitutes a top layer Ga atom, but because of its smaller size its vertical position is between the top most and the second gallium layers. As in the ideally GaN (0001) bulk terminated surface, in the GaN(000 (1) over bar) surface, the boron atom replaces a topmost gallium atom, but now it forms a bond with a second layer N atom. In the most stable configuration there is a rearrangement of the top layer Ga atoms, and the final configuration cannot be considered an ad-atom structure. These results show the same trends of other metal ad-atoms adsorbed on GaN surfaces, but the specific adsorption geometries change due to the small size of the B atom.

• 出版日期2012-1-1