Atomic and electronic structures of6H−SiC(112¯0)

Abstract

The atomic and electronic structures of the nonpolar $6H\ensuremath{-}\mathrm{SiC}(112\ifmmode\bar\else\textasciimacron\fi{}0)$ surface are investigated by high-resolution medium-energy ion scattering (MEIS) combined with photoelectron spectroscopy with synchrotron-radiation light. The clean surfaces prepared show a clear $1\ifmmode\times\else\texttimes\fi{}1$ reflective high energy electron diffraction pattern. The present MEIS analysis has revealed that the surface has a Si adlayer of 0.5 ML $(1\mathrm{ML}=1.49\ifmmode\times\else\texttimes\fi{}{10}^{15}{\mathrm{a}\mathrm{t}\mathrm{o}\mathrm{m}\mathrm{s}/\mathrm{c}\mathrm{m}}^{2})$ as the topmost layer and the second-layer, consisting of Si and C, is rumpled significantly. The interplanar distance between the second- and third-layer Si planes is expanded by $0.026\ifmmode\pm\else\textpm\fi{}0.02\AA{}$ and, in contrast, the interplanar distance between the second- and third-layer C planes is contracted by $0.021\ifmmode\pm\else\textpm\fi{}0.02\AA{}.$ The observed $\mathrm{Si}\ensuremath{-}2p$ core-level spectra consist of the bulk (B) and three surface components $(S1,$ $S2,$ and $S3),$ whose binding energies are $100.8\ifmmode\pm\else\textpm\fi{}0.1,$ $99.5\ifmmode\pm\else\textpm\fi{}0.1,$ $100.3\ifmmode\pm\else\textpm\fi{}0.1,$ and $101.2\ifmmode\pm\else\textpm\fi{}0.1\mathrm{eV},$ respectively. Two surface components labeled $S1$ and $S2$ are assigned to the Si adlayer and the second-layer Si, respectively. On the other hand, the C $1s$ core level has only one Gaussian component with a binding energy of $284.1\ifmmode\pm\else\textpm\fi{}0.4\mathrm{eV}.$ The observed valence band spectra are semiconductor-like and include surface-state levels with slightly dispersive structures.