Ab initio-based approach to adsorption-desorption behavior on the InAs(1Â 1Â 1)A heteroepitaxially grown on GaAs substrate

The surface reconstructions and adsorption-desorption behavior on InAs(1 1 1)A heteroepitaxially grown on GaAs(1 1 1) substrate are systematically investigated using our ab initio-based approach incorporating the chemical potentials of In atom and As molecules in the gas phase as functions of temperature and beam equivalent pressure. This approach is also applied to qualitatively clarify the dependence of the surface-related properties on the film thickness of InAs considering various models, such as the InAs fully relaxed and coherently grown without/with GaAs interface. The calculated results imply that the most stable surface structure of the InAs(1 1 1)A is the In-vacancy surface at high temperatures including conventional growth conditions, whereas the As-trimer surface appears at low temperatures. In addition to these surface structures, As-adatom structure is newly found as a stable phase only in one atomic double-layer of InAs coherently grown on GaAs. This is because the charge redistribution due to the As adsorption strengthens the interatomic bonds with the surface In atom to stabilize the As-adatom surface. Distinctive features in the In adsorption are shown depending on the film thickness with respect to the computational models. Furthermore, the In adsorption on the In-vacancy surface does not occur without simultaneous As adsorption under conventional growth conditions. This reveals that the self-surfactant effect is crucial for the growth processes of InAs similarly to the GaAs growth.