C60 single domain growth on indium phosphide and its reaction with atomic hydrogen

The growth of C₆₀ fullerene films on InP(001)-(2×4) was studied under ultrahigh vacuum conditions. The spectral signature of the C₆₀ films was measured using high resolution electron energy-loss spectroscopy. Our data show that the molecules are bonded weakly to the substrate, leading to three-dimensional (3D) cluster formation of C₆₀ at the initial stages of deposition. This is indicated by spectroscopic and microscopic observations. Surprisingly, low-energy electron diffraction and scanning tunneling microscopy measurements reveal that further molecule deposition forms a well ordered single domain film. From the analysis of our microscopic data, we have determined that the C₆₀ film has an fcc (111) orientation. The influence of structural inhomogeneities and indium clusters, which are the most prevalent defects of the InP(001)-(2×4) surface, on the molecular film properties was studied. A shift of the substrate carrier plasmon under annealing was detected. The stability of the C₆₀ film under exposure to atomic hydrogen was investigated. High reactivity of the molecules was detected. Further exposure does not change the surface, which indicates the formation of a stable coverage by the chemical modification.