Investigation of the atomic structure of surfaces by means of forward scattering of medium energy electrons

The atomic structure of several surfaces has been investigated on the basis of the real space patterns formed by forward scattering of medium energy electrons from the surface. The images of the Cu(111) surface show not only that the surface has the three-fold symmetry but also that the fee stacking sequence persists up to the topmost atomic layer. The images of the Si (111) ( root 3 ?? root 3) R30??-In surface support that In atoms occupy the T4 sites on the surface, rather than the H3 sites. In the case of Ge(111)( root 3 ?? root 3) R30??-Ag surface the images indicate that the honeycomb-chained-triangle (HCT) model is correct. The success of these applications shows that reliable structural information of surfaces can be obtained quite straightforward by means of forward scattering of medium-energy electrons, instead of via complicated calculations such as involved in LEED crystallography.EI081241-12424