Inverse-photoemission spectroscopy of the unreconstructed, ideally H-terminated Si(111) surface

The chemically prepared H/Si(111)-(1\ifmmode\times\else\texttimes\fi{}1) surface has been studied by k-resolved inverse-photoemission spectroscopy (KRIPES) along the two main directions (\ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} K\ifmmode\bar\else\textasciimacron\fi{} and \ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} M\ifmmode\bar\else\textasciimacron\fi{}) of the surface Brillouin zone. Two conduction bands are evident at 2.6 and 4.0 eV at \ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} and display some dispersion. A marked asymmetry is observed in their dispersion along the M\ifmmode\bar\else\textasciimacron\fi{} '\ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} M\ifmmode\bar\else\textasciimacron\fi{} direction. This asymmetry is a manifestation of the different contributions of the eigenstates associated with ${\mathbf{k}}_{\mathrm{\ensuremath{\parallel}}}$ and -${\mathbf{k}}_{\mathrm{\ensuremath{\parallel}}}$ to the KRIPES cross sections.