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 microm for the sample implanted at 1 × 10 13 ions cm −2 and at higher doses it decreases. Raman measurements at higher doses show the loss of sp 3 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 × 10 15 ions cm −2 corresponds to an implantation-induced sp 3 -to-sp 2 transformation without graphitization.