On clean and Ni-contaminated surfaces of Si(110), experiments of low-energy electron diffraction (LEED) and Auger-electron spectroscopy (AES) were carried out under various heat treatments. The Si(110) clean surface has a ‘‘16×2’’ structure and it transforms reversibly to 1×1 at 740 °C. On the other hand, Ni-contaminated surfaces exhibit several surface superstructures at room temperature, e.g., the 4×5, 2×1, and 5×1, depending on the heat treatments. Moreover, it is found that these structures are closely correlated with Ni concentration at the surface. Quantitative Auger-electron analyses show that a thickness of the Ni-contaminated layer varies from several angstroms to 20 Å and the surface Ni concentration changes from 7% to 1%, depending on the heat treatment. These variations give rise to changes of the surface superstructure depending on the heat treatment.

• Received 14 December 1984

DOI:https://doi.org/10.1103/PhysRevB.31.5183