Surface electronic structure of Si(111)7×7-Ge and Si(111)5×5-Ge studied with photoemission and inverse photoemission

Abstract

Angle-resolved photoemission and inverse photoemission have been used to study the electronic structure of Si(111)7\ifmmode\times\else\texttimes\fi{}7-Ge and Si(111)5\ifmmode\times\else\texttimes\fi{}5-Ge surfaces. For both surfaces, one unoccupied and three occupied surface-state bands have been mapped along the \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{} lines in the 1\ifmmode\times\else\texttimes\fi{}1 surface Brillouin zone. These bands have characteristics similar to those of the surface-state bands observed for the clean Si(111)7\ifmmode\times\else\texttimes\fi{}7 surface. Quantitative differences in the dispersions seem to correlate with the Ge content in the surfaces rather than with surface periodicity.