Adatom electronic structure of the Si(111)7×7 surface

With the technique of k-resolved inverse photoemission a pronounced dispersing surface state is observed for the Si(111)7×7 surface, 0.5 eV above the Fermi level. This state bears strong similarities with the empty adatom states observed on Si(111) ̂>3 × ̂>3 -Al, -Ga, and -In surfaces, and originates from the 12 adatoms in the 7×7 surface cell observed with scanning-tunneling microscopy. Reinterpretation of recent band-structure calculations identify the origin of all major surface states observed. © 1987 The American Physical Society.