Role of Oxygen and Fluorine in Passivation of the GaSb(111) Surface Depending on Its Termination

Abstract

The mechanism of the chemical bonding of oxygen and fluorine on the GaSb(111) surface depending on its termination is studied by the projector augmented-waves method within density functional theory. It is shown that on an unreconstructed (111) surface with a cation termination, the adsorption of fluorine leads to the removal of surface states from the band gap. The binding energy of fluorine on the cation-terminated surface in the most preferable Ga-T position is lower by ~0.4 eV than that of oxygen, but it is significantly lower (by ~0.8 eV) on the anion-terminated surface. We demonstrate that the mechanism of chemical bonding of electronegative adsorbates with the surface has an ionic–covalent character. The covalence of the O–Sb bond is higher than the F–Sb one, and it is higher than both O–Ga and F–Ga bonds. Trends in the change in the electronic structure of the GaSb(111) surface upon adsorption of fluorine and oxygen are discussed. It is found that an increase in the oxygen concentration on the Sb-terminated GaSb(111) surface promotes a decrease in the density of surface states in the band gap.

Surface Atomic Arrangement of Aluminum Ultra-Thin Layers Grown on Si(111)

“…Figure 2 a shows the RHEED pattern of the Al films grown on the Si(111)-7 × 7 surface. The image was captured in the [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ] azimuth direction after 2 h of annealing. The specular beam intensity indicated by spots A and B identifies the Si(111)-1 × 1 lattice originating from the bulk.…”

“…Knowing the details of the surface structure and its crystalline arrangement is critical for the deposition of ultrathin metallic films, especially if protection against atmospheric oxidation is required. The metallic surface is harmed by atmospheric exposure, which causes partial amorphization and severely limits its functionality [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. This affects surface electrical conductivity and controls the current efficiency in many applications [ 12 , 13 , 14 ].…”