Low energy ion irradiation studies of fullerene C-70 thin films-An emphasis on mapping the local structure modifications

摘要

Metal matrix composites have a diverse range of applications. We have probed local structural modifications taking fullerene C-70 as a model matrix material. In this study, thin films of fullerene C-70 were grown on polished silicon and quartz substrates by resistive heating of fullerene Cm In order to understand local structural changes, these semi-crystalline films were irradiated with 120 keV N+ ions at different fluences ranging from 1 x 10(13) to 3 x 10(16) ions.cm(-2). Microscopic analysis shows an increase in topological roughness up to a fluence of 1 x 10(15) ions.cm(-2) and then a decrease. The size of the particles decreases with increase in the fluence. Various spectroscopic analyses conducted on differently irradiated fullerene C-70 films show that the bandgap decreases with the increase in the fluence which will increase the conductivity of the irradiated thin films. These results are proved by I-V measurements showing the decrease in the resistivity at higher fluences. Therefore, this characteristic trait makes fullerene C-70 to be used as a prominent matrix component in the composites. Raman spectroscopic investigations reveal that C-70 is completely transformed into amorphous carbon at a fluence of 3 x 10(16) ions.cm(-2). Different vibrational modes in FT-IR are also reported in the present work.