Modification of C60 thin films by ion irradiation

Transformation of C60 thin films on Si(111) substrates by irradiation with 7-MeV 12C2+ ions is investigated. Raman-spectroscopy analysis reveals that irradiation of C60 films at low dose causes suppression of photopolymerization. The C60 films are transformed into a form of amorphous carbon at high dose. Slight C60 molecules still exist in the film up to the dose of 1.1×1016/cm2. AFM analysis shows that as-prepared insulating films become conductive after irradiation up to the dose of 1.1×1016/cm2, which results from conductive carbon species due to dissociation of the C60 molecule.