DFT study of the effect in surface energy of metallic overlayers in semiconductors

The surface energy of various systems: semiconductors (Ge and Si), metals (Ag and Pb) and metallic overlayers on semiconductors Ag/Ge and Pb/Si) have been calculated using a DFT approximation. The Pb(111) and Ag(111) adlayers on Si and Ge(111) surfaces had been modeled using the periodic supercell approach. Self-consistent field energy periodic calculations for bulk and surfaces of Ge, Si, Pb and Ag, with 12, 11, 10, 9, 8, 7 and 6 layers and SC12-nMn (where SC is Ge or Si; M is Ag and Pb, respectively and n is the number of layers) metallic adlayers on semiconductor super-system slab models were calculated using plane wave density functional theory, in particular employing the Perdew Wang (PW91) functional. The metallic adlayers on semiconductors modify its surface energy and vice versa. The values for SC12-nMn systems follow a sinusoidal trend in similar way to for semiconductors, but softer. The surface energy values lay in between those corresponding to semiconductors and metals. These results indicate that if the number of metallic overlayers on a semiconductor can be controlled then the surface energy can be addressed.