The structural modification due to 2 MeV 4He ion irradiation with doses ranging from 0.55 to 2.7 × 1016/cm2 is investigated for a-C: H films prepared by a rf glow discharge of methane gas. Reflectance spectra from the films with and without irradiation are measured in the photon energy range up to 25 eV. An effective medium approximation (EMA) is applied to analyze the dielectric function obtained from the reflectance spectra. The EMA results show that the polymeric component decreases with the increase of the ion beam dose. The effect of the He ion irradiation is to increase σ-π hybridization in the graphitic phase.
ASJC Scopus subject areas
- Nuclear and High Energy Physics