First-Principles Calculations of Atomic and Electronic Properties of Tl and In on Si(111)

The atomic and electronic structures of T1 and In on Si(111) surfaces are investigated using the firstprinciplestotal energy calculations.Total energy optimizations show that the energetically favored structure is 1/3 MLT1 adsorbed at the T_4 sites on Si(111) surfaces.The adsorption energy difference of one T1 adatom between (3^(1/2)×3^(1/2))and (1×1) is less than that of each In adatom.The DOS indicates that T1 6p and Si 3p electrons play a very importantrole in the formation of the surface states.It is concluded that the bonding of T1 adatoms on Si(111) surfaces is mainlypolar covalent,which is weaker than that of In on Si(111).So T1 atom is more easy to be migrated than In atom in thesame external electric field and the structures of T1 on Si(111) is prone to switch between (3^(1/2)×3^(1/2)) and (1×1).

The atomic and electronic structures of T1 and In on Si（111） surfaces are investigated using the firstprinciples total energy calculations. Total energy optimizations show that the energetically favored structure is 1/3 ML T1 adsorbed at the T4 sites on Si（111） surfaces. The adsorption energy difference of one T1 adatom between （√3 × √3） and （1 × 1） is less than that of each In adatom. The DOS indicates that TI 6p and Si 3p electrons play a very important role in the formation of the surface states. It is concluded that the bonding of TI adatoms on Si（111） surfaces is mainly polar covalent, which is weaker than that of In on Si（111）. So T1 atom is more easy to be migrated than In atom in the same external electric field and the structures of T1 on Si（111） is prone to switch between （√3 × √3） and （1 × 1）.