Study of Electronic Structures of Ge(111)7 ×7-Sn and Ge(111) “2 ×8” Surfaces by Angle-Resolved UPS

Angle-resolved ultraviolet photoemission measurements have shown that the surface electronic structure of the Ge(111)7 ×7-Sn surface is essentially the same as that of the Si(111)7 ×7 surface. Metallic surface states of the Ge(111)7 ×7-Sn surface reveal a slight dispersion of an approximate 2 ×2 periodicity. The so-called dangling- and the back-bond surface states of the Ge(111)“2 ×8” surface also show a slight dispersion. The dangling- and the back-bond surface states of the Ge(111)7 ×7-Sn surface lie at nearly the same binding energies as those for the Ge(111)“2 ×8” surface rather than those for the Si(111)7 ×7 surface.