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

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