Ion Beam Crystallography at the Si(100) Surface

Abstract

The geometric structures of the clean 2\ifmmode\times\else\texttimes\fi{}1 reconstructed and the hydrogen-stabilized (1\ifmmode\times\else\texttimes\fi{}1)2H Si(100) surface have been studied by means of ion channeling and blocking. The latter surface appears to be contracted by 0.08\ifmmode\pm\else\textpm\fi{}0.03 \AA{} and has a surface Debye temperature of \ensuremath{\sim}230 K. For the 2\ifmmode\times\else\texttimes\fi{}1 surface it is shown that only the surface dimer models by Appelbaum and Hamann and by Chadi agree well with the backscattering data. The silicon atoms in the very surface are displaced more than 0.45 \AA{} in the surface dimer direction, but those in deeper layers are displaced less than \ensuremath{\sim}0.2 \AA{}.