Behaviors of surfactant atoms on Si(001) surface

The behaviors of surfactant atoms for thin film growth on the Si(001) surface formed by molecular beam epitaxy were observed. At first, heterointerfaces on Si/Ge and Ge/Si without surfactant effect were investigated and are discussed on the basis of thermodynamics of surfaces and surface diffusion. The mechanism of island formation as a later stage of Stranski-Krastanov growth mode is also discussed. Surfactant effects of Bi atoms on the heteroepitaxial structures were investigated experimentally. Behavior of Sb as a surfactant was also observed and compared with the results of Bi. Mechanisms for improvements in the abruptness at heterointerfaces of Si/Ge/Si as well as suppression of island formation are discussed. The formation of atomic-scale wires of Bi was observed. The structure of Bi wires at high temperatures is described.