ION-IMPLANTATION EFFECTS IN LASER-DEPOSITED AMORPHOUS-CARBON FILMS

Ion implantation effects have been studied in the pulsed-laser-deposited amorphous carbon (a-C) films having a diamond-like character. 80 keV Ar+ ions were implanted at various doses, and the optical and electrical properties of the films were studied as a function of ion dose. It was observed that the electrical resistivity and optical band gap decrease as the ion dose increases. The transparency increases from 80% (for the as-deposited a-C) to over 97% in the wavelength range 2.5-4-mu-m for the sample implanted at 1 x 10(13) ions cm-2 and at higher doses it decreases. Raman measurements at higher doses show the loss of sp3 hybridized carbon atoms with no sign of microcrystallinity. The absence of the Raman contribution at 600 and 1275 cm-1 in samples implanted at doses greater than 1 x 10(15) ions cm-2 corresponds to an implantation-induced sp3-to-sp2 transformation without graphitization.