AS ON INP(110) STUDIED WITHIN DENSITY-FUNCTIONAL THEORY

We present a comprehensive picture of the As adsorption on the InP(110 ) surface based on nb initio density-functional calculations. The bond ing behavior of single As adatoms is investigated by the calculation o f the Bom-Oppenheimer energy face. The adatom motion is characterized by an attractive interaction and a pronounced diffusion channel along [1(1) over bar0$]. The translationally invariant As/InP(11O)1x1 system is discussed in terms of an ordered As monolayer and an exchange reac tion between surface P atoms and As adatoms. The epitaxial continued l ayer structure represents the ground state of the initial-stage interf ace between the ordered As monolayer and the InP(110) surface. The exc hange-reacted surface with one InAs(110) top layer is energetically st able over a wide range of the In and As chemical potentials, whereas t he monolayer adsorption occurs preferentially for As-and P-rich prepar ation conditions. We calculate electronic and vibrational features of the interface and compare with the available experimental data.