Atomic and electronic structure of the K/Si(111)√3x√3R30°-B chemisorption system

Ab initio plane-wave pseudopotential density functional theory (DFT) calculations have been carried out to determine the atomic and electronic structure of the K/Si(111)√3x√3R30°-B adsorption system at 1/3 monolayer coverage. Chemisorption of the potassium atoms has been found to leave the topology and bonding structure of the Si(111)√3x√3R30°-B substrate essentially unchanged. The results also show that the lowest energy K/Si(111)√3x√3R30°-B structures are very similar to the most energetically favorable geometries for the K/Si(111)7x7 chemisorption system. The minimum energy configuration has been found to be a structure in which the potassium atoms are positioned near the hollow H₃ sites, the boron atoms occupy the subsurface S₅ positions, and the silicon adatoms are located at the T₄ sites. The electronic structure of this lowest-energy K/Si(111)√3x√3R30°-B configuration has been found to be metallic.