Epitaxial thin films of C70: Growth and structure characterization

Epitaxial thin films of C70 have been grown on (001) mica substrate by resistive evaporation at a vacuum pressure of about 10(-3) Pa.The orientational ordering and the nature of the defects presented in the films were assessed by transmission electron diffraction and electron microscopy. The fundamental structure of the C70 crystals is face-centered cubic with the lattice parameter a0 = 1.50 nm, but forbidden reflections resulted from hcp stacking were also detected which are usually appeared in the prior study of alloys with low stacking fault energy and the solid C60. Furthermore, we also studied the films deposited on (001) NaCl and Si single crystals and the results show these substrates promoted polycrystal growth under the same evaporation conditions where epitaxy was observed on mica.