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

The structural changes occurring during the vacuum annealing, accompanied by Ni in C-60/C-70 + 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 2 wt% of Ni. Obtained layers were annealed under the pressure of 10(-5) Torr at the temperatures of 770-820 K. 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 similar to 750 nm) 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 C-60 molecule vibrational band (broaden and shifted A,(2) vibrational mode), the bands connected to vibrational mode of nanotubes (1565 cm(-1)) and graphite (1585, 1620 cm(-1)) were observed. AFM images exhibited the existence of hillocks (diameter in the base similar to 300nm) surrounded by needle-like objects (diameter 20-30 nm) protruding from the substrate. (C) 1999 Elsevier Science Ltd. All rights reserved.