Growth of a uniaxial incommensurate C60 lattice on Ge(100)2×1

Abstract

Room temperature adsorption of C60 on a Ge(100)2×1 surface from a few molecules to a full monolayer coverage was studied using scanning tunneling microscopy and low-energy electron diffraction. The distribution of the C60 molecules at the early stage of adsorption indicates that the molecules dissipate their in-plane kinetic energy primarily through collisions with other bound C60 molecules, rather than steps and vacancies of the surface. Upon thermalization, the molecules reside exclusively in troughs between dimer rows of the substrate. Clustering of the molecules takes place from outset of the adsorption, and the molecules in clusters adopt either a four-dimer or a two-dimer binding site. Subsequent adsorption proceeds in an orderly fashion, leading to the growth of two-dimensional islands and finally an overlayer with a uniaxial incommensurate C60 lattice structure. The adsorption of C60 molecules appears to affect the buckling of the substrate dimers.