Theoretical study of adsorption of gallium and gallium nitrides on Si(1 1 1)

Adsorption of gallium (Ga, Ga+) and gallium nitrides (GaN, GaN+, GaN2, GaN 2 + ) on a model Si(1 1 1) surface was studied by density functional theory calculations. Significant binding is found for all the species considered, with binding energies up to 6.13 eV. For GaN, GaN2, and GaN 2 + the lowest energy structures are those with the adsorbate forming a bridge between the Si adatom and rest atom, while for GaN+ it is a vertical structure connecting to Si via N. Furthermore, it is found that adsorbed GaN and GaN+ are essentially the same species, resembling free GaN−.