SURFACE STUDY OF THIN EPITAXIAL COSI2/SI(100) LAYERS BY SCANNING TUNNELING MICROSCOPY AND REFLECTION HIGH-ENERGY ELECTRON-DIFFRACTION

Epitaxial single-domain CoSi2(100) layers have been grown on Si(100) by the use of a template technique. In situ scanning tunneling microscopy (STM) and reflection high-energy electron diffraction (RHEED) have been used for a detailed surface study. The dependence of the surface step structures on the stoichiometry is described. The transformation of the Co-rich C-surface to the Si-rich S-surface at about 500-degrees-C is related to the formation of pinholes. The (square-root 2 x square-root 2)R45 reconstruction of the C-surface and the (3 square-root 2 x square-root 2)R45 as well as a newly discovered (square-root 2 x square-root 2)R45 of the S-surface have been resolved in real space and are described in detail. Different structural models are discussed. A (2 x 2) reconstruction is related to the transition from the C-surface to the S-surface. The occurrence of misoriented CoSi2(011) grains and the dependence of the critical thickness for strain relaxation on the detailed template recipe have been analyzed by STM.