A comprehensive study of SHI irradiated fullerene C60 thin films: Polymerization to amorphization

Abstract

Fullerene C60 thin films with a thickness of ∼120nm were synthesized by thermal evaporation method on glass substrate. The deposited thin films are irradiated with 90MeV Ni ions in the fluence range from 1×109 to 3×1013 ions/cm2. The pristine and irradiated fullerene C60 thin films are examined to study the effect of energy deposition by 90MeV Ni ions on the optical and structural properties by UV–visible absorbance spectroscopy and Raman spectroscopy, respectively. UV–visible absorbance spectroscopy study reveals that the absorbance peaks decline with the fluence and at particular fluence (∼3×1013 ions/cm2) all the absorbance peaks disappear. Apart from this, a decrease in band gap has also been observed with increasing fluence. Raman study confirms that the effect of 90MeV Ni ion irradiation is observed in two phases. In the lower fluence region, polymerization of C60 molecules is observed and in higher fluence region, destruction of the molecules comes into picture. At fluence 3×1013 ions/cm2, fullerene C60 thin film transformed into amorphous carbon (a-C). The transformation of fullerene into a-C is also confirmed through conductivity measurement.