Topography and structure of C60/C70+Ni film containing carbon nanotubes grown perpendicularly to the substrate

Abstract

The structural changes occurring during the vacuum annealing, accompanied by Ni in C60/C70+Ni layers were studied by atomic force microscopy (AFM), transmission electron microscopy (TEM), electron diffraction (ED) and Raman spectroscopy (RS). The layers were prepared by thermal deposition method and contained 2wt% of Ni. Obtained layers were annealed under the pressure of 10-5Torr at the temperatures of 770–820K. The initial layers showed mostly amorphous fullerenes structure what was confirmed by TEM, ED and Raman spectroscopy. The hillock-like topography of surface (hillock base diameter ∼750nm) was observed by AFM. No Ni or graphite crystalline structure were observed for initial layers. Annealed layers were composed of nanotubes with cylindrical shape, fullerenes and graphite grains what was confirmed by TEM and ED. In the Raman spectra, except of distorted C60 molecule vibrational band (broaden and shifted Ag(2) vibrational mode), the bands connected to vibrational mode of nanotubes (1565cm-1) and graphite (1585, 1620cm-1) were observed. AFM images exhibited the existence of hillocks (diameter in the base ∼300nm) surrounded by needle-like objects (diameter 20–30nm) protruding from the substrate.