New surface atomic structures for column V overlayers on the (110) surfaces of III–V compound semiconductors

Two new minimum-energy surface structures have been identified for p(1×1) overlayers of Sb on the (110) surface of III–V compound semiconductors using a tight-binding total-energy formalism previously developed for these systems. The first is the ‘‘epitaxical on top structure’’ (EOTS) in which Sb zig–zag chains are commensurate with, and on top of, the Ga–As unreconstructed surface zig–zag chains. This structure differs from the previously found ‘‘epitaxical continued layer structure’’ (ECLS) by virtue of the registry of the Sb chains ‘‘on top of ’’ rather than ‘‘in between’’ the substrate Ga–As chains. Like the ECLS, the EOTS is compatible with both scanning tunneling microscopy (STM) and photoemission data. The second new structure is the ‘‘epitaxical overlapping chain structure’’ (EOCS) in which the Sb chains are 180° out-of-phase with, and on top of, the Ga–As substrate chains. This structure is, however, incompatible with both low-energy electron diffraction and STM data for GaAs(110)–p(1×1)-Sb. Computations for GaP(110)–p(1×1)-Sb and InSb(110)–p(1×1)-Sb reveal that the energy difference between the EOTS and ECLS is approximately constant over this range of overlayer/substrate lattice mismatch.