Theoretical Study of Adsorption and Diffusion of Group IIIA Metals on Si(111)

Abstract

Adsorption of group IIIA elements (M = B, Al, Ga, and In) on a model Si(111) surface was studied by density functional theory calculations. Eight stable structures were determined for the M adsorbed species. The incorporation of the M atoms on the Si surface is investigated, and the energy barriers for the incorporation are calculated. The binding energy of the lowest calculated minimum of chemisorbed M at Si(111), after correcting for the basis set superposition error, is 6.3 (B, S5 substitutional site), 3.4 (Al, T4 adsorption site), 2.9 (Ga, T4), and 2.5 (In, T4) eV. Our results are in good agreement with previous experimental work, where available. The activation energy barrier from the T4 to the H3 adsorption site is 1.2 (Al), 1.1 (Ga), and 0.7 eV (In); the activation energy barrier from the lowest energy structure with M connected to the surface at a dangling bond to a precursor of T4 is 0.5 (B), 1.6 (Al), 1.7 (Ga), and 1.9 eV (In).