CHARACTERIZATION OF DIAMOND-LIKE CARBON-FILMS BEFORE AND AFTER HEAVY ENERGETIC ION IMPLANTATIONS

Hydrogenated diamond-like carbon films were implanted by 110 keV Fe+ a t doses ranging from 1 x 10(13) to 5 x 10(16) ions cm(-2). The film re sistivities and the infra-red transmittances of the specimens were det ermined as functions of the implanted doses. Raman spectra and the inf ra-red transmittances of the film layers were used to characterize the structural changes of the implanted films. It was found that, when th e implantation dose was higher than about 5 x 10(14) or 1 x 10(15) ion s cm(-2), the film resistivity and the total infra-red transmittance o f the specimens decreased significantly. However, when the dose was sm aller than this value, the resistivity decreased firstly and then incr eased with dose and the measured values were higher than those of corr esponding as-grown ones. The infra-red transmittance of the specimens was also improved to some extent under the lower dose range. By using structural characterization results, especially the infra-red transmit tances of the film layers, we conclude that the electrical and optical property changes at doses higher than about 5 x 10(14) or 1 x 10(15) ions cm(-2) were due to the following changes, i.e., the decrease in t he population of both sp(2) C-H and sp(3) C-H bonds (compared with tha t of sp(3) C-H bonds, the decrease in speed of sp(2) C-H bonds is smal ler), the decrease of bond-angle disorder and the increased population of sp(2) C-C bonds. However, at doses between 1 x 10(14) and 5 x 10(1 4) or 1 x 10(15) ions cm(-2), the implantation induced increase of C-H bonds was responsible for the observed property changes. Compared wit h the previous reports, the novelty of the present work is: the IR tra nsmittance curves of the single film layers give us direct evidence fo r the changes of different C-H bonds with increasing ion dose and thus proved the transformation mechanism proposed previously.