THE IRRADIATION EFFECT OF MEV PROTONS ON DIAMOND-LIKE CARBON-FILMS

Diamond-like carbon films, prepared by dual-ion beam sputtering deposition on glass substrate, were irradiated by 1.5 MeV protons under doses ranging from 1 X 10(13) to 1 X 10(17) ions/cm2. The electrical resistivity, the infrared transmittance and the Raman spectrum were used to characterize the films. It was shown that the irradiation reduced both the film resistivity and the infrared optical transmittancy of specimens obviously and there existed a critical ion dose (1 x 10(15) ionS/cm2) for the onset of the reductions. The aging effect of the irradiated films in air was also studied at room temperature and it was found that higher increases in resistivity appeared for films irradiated by higher doses. It was concluded that the breaking of C-C bonds, C-H bonds and the release of hydrogen atoms are responsible for both the decreases in resistivity and in optical transmittancy. The critical ion dose is a threshold for the release of hydrogen. The aging effect of resistivity was caused by the passivation of dangling bonds in air.