Two-dimensional Ga-induced magic clusters on the Si surface: a density functional study

Density functional B3LYP/LANL2DZ and B3LYP/6-31G* calculations have been carried out to study the structure and stability of model Gan(n+1)/2Sin(n−1)/2H3n+n(n−1)/2 and Gan(n+1)/2Sin(n−1)/2(SiH3)3nHn(n−1)/2 clusters (n=2, 3, and 4). The clusters are thermodynamically stable, have a triangular shape, and consist of fused non-planar Ga3Si3 hexagons with three external Si–Ga bonds in the triangle vertices. The Si–Ga bond strength in the clusters is estimated as 40–42 kcal/mol. The model clusters simulate the two-dimensional Ga-induced triangular magic clusters on the Si(111) surface recently observed experimentally. The cluster growth process is predicted to be exothermic.