Heating effect on C-60 films during microfabrication: structure and electrical properties

Thin films of C-60 fullerene were prepared by vacuum evaporation on cold substrates of thermally oxidized and bare silicon wafers. The effect of thermal annealing on C-60 films was investigated by means of Raman, atomic force microscopy and X-ray diffraction. It was found that the densification of C-60 films Occurred at low temperature range whereas the change of C-60 structure to microcrystalline graphite occurred when high temperature annealing. The C-60 films annealed at 100degreesC have the highest packing density, low surface roughness, high degree of crystallinity and stable ohmic contacts. These results clearly indicated that the electronic properties of C-60 can be improved by heating in low temperature range without affecting the heat treatments in the microfabrication. (C) 2004 Elsevier Ltd. All rights reserved.