Surface electronic structure study of Au/Si(111) reconstructions: Observation of a crystal-to-glass transition

The alpha-root3xroot3, beta-root3xroot3, and 6x6 surfaces of Au/Si(111) have been studied by angle-resolved photoelectron spectroscopy (ARPES). The alpha-root3xroot3 surface shows four surface state bands, one of which is a dispersing metallic band. Except for one nondispersing band near the Fermi level, the beta-root3xroot3 surface shows surface bands that are similar to those of alpha-root3xroot3. Eight surface state bands have been found on the 6x6 surface instead of two as reported in the literature. Seven of these surface states are broadened into three, when the 6x6 phase is transformed into the quenched beta-root3xroot3 phase just by annealing followed by quick cooling. The transition between the 6x6 and quenched beta-root3xroot3 phases is consistent with a crystal-glass transition.