Halogen adsorption at an As-stabilized $\beta$2–GaAs(001)–(2$\times$4) surface

Halogen (F, Cl, Br, and I) adsorption at an As-stabilized GaAs (001) surface with the $\beta$2–(2$\times$4) reconstruction is studied using the plane-wave projected-augmented wave method. The effect of halogens on the structural and electronic characteristics of the semiconductor surface is analyzed. The $T'_{2}$ site at the missing row edge is shown to be the energetically most favorable for the adsorption of F, Cl, and Br, whereas I prefers the $H_3$ site between adjacent arsenic dimers in the third layer from the surface. Ga-halogen bond formation suggests that charge is transferred via the depletion of occupied orbitals of the As-dimer surface atoms, which leads to the weakening of Ga–As bonds in the substrate. The weakening of bonds between substrate-surface atoms due to the interaction of halogens with the surface is estimated.