Peculiar diffusion of C₆₀ on In-adsorbed Si(111)√3 × √3-Au surface

In-accumulated Si(111)√3 × √3-Au surface represents a highly-ordered homogeneous Au/Si(111) reconstruction with a two-dimensional gas of In adatoms on it. Regularities of C₆₀ migration on this surface have been elucidated through analysis of C₆₀ island density as a function of growth temperature and deposition rate in the framework of the rate equation theory and simulation of C₆₀ migration using density-functional-theory calculations. The critical cluster size has been found to be i = 1 for the whole temperature range studied, from 110 to 240 K, while activation energy for C₆₀ diffusion varies from (99 ± 18) meV at 110 ÷ 140 K to (370 ± 24) meV at 160 ÷ 240 K. This finding has been accounted to the peculiarity of C₆₀ migration in a labyrinth built of In adatoms on the Si(111)√3 × √3-Au surface, namely, at low temperatures C₆₀ migration is confined within the labyrinth channels, while at high temperatures C₆₀ molecules possess enough thermal energy to surmount the labyrinth walls.