Adsorption energies of Al, Ga, In, Tl on Si(111)-7x7

Abstract

The energy of adsorption of group III elements like Al, Ga, In, Tl on Si (111) is calculated based on density-functional theory (DFT). VASP code in conjunction with ultrasoft potentials within the generalized-gradient approximations (GGA) are used for the calculation. The cutoff energy of 150 eV and one special k point are used, which gives an energy error of a few meV per adatom. The lowest-energy site is top-site for Al, Ga and bridge-site for In, Tl. The highest-energy site is hollow-site for Al, Ga, In and top-site for Tl. The dangling bond saturation and coordination number are the two factors that govern the adatom stability. Coordination number is more important for Al but with increasing metal atom's radius factor, dangling bond saturation becomes more essential than coordination number.