Real-space observation of<i>π</i>-bonded chains and surface disorder on Si(111)2×1

Abstract

Scanning tunneling microscopy is used to confirm the \ensuremath{\pi}-bonded chain structure of the Si(111)2\ifmmode\times\else\texttimes\fi{}1 surface. Both the amplitude and voltage dependence of the vertical corrugation exclude the buckling model for the structure of this surface. Spectroscopic measurements of the tunneling current versus voltage identify a band gap for the 2\ifmmode\times\else\texttimes\fi{}1 surface states. Spatial images of disorder-related states are obtained by tunneling at energies inside of this band gap.