FLUORINE IMPLANTATION-INDUCED ESR SPLITTING IN A-C-H THIN-FILMS

Multiple energy fluorine implantation into rf glow-discharge a-C:H has been performed with the implanted F concentration C(F) ranging from 1 x 10(17) to 3 x 10(21) cm-3. It is discovered that a splitting in the ESR spectra measured in dark at room temperature at the X-band has be en induced by the implanted fluorine atoms in these films. The ESR spe ctra show a large main peak due to carbon dangling bonds with g-value g1 = 2.0027 +/- 0.0002. Hyperfine splitting (HFS) signals, one at each side of the main peak, are observed with an effective g-value g(eff) = 1.9981 +/- 0.0004, and each of the HFS signals is composed of two Ga ussian components showing the anisotropy of the hyperfine splitting. F or C(F) higher than about 10(20) CM-3, the large main resonance is als o found to be composed of one big Lorentzian component of g-value g1 a nd one small Gaussian component of g-value g2 = 2.0025 +/- 0.0003. The C(F) dependence and the annealing behavior of these ESR components ha ve been studied. It is found that the HFS signals exhibit a peculiar C (F) dependence and do not show up at some intermediate C(F) value rang e. On the other hand, while all HFS signals have been annealed out aft er annealing at 200-degrees-C, the small g2 component persists even af ter annealing at 250-degrees-C. A model based on the spin polarization effect has been proposed to attribute the HFS signals to be arisen fr om interaction between pi electrons of the carbon atoms and the 2p orb itals of the fluorine atoms. The possible origin of the 92 resonance h as also been discussed and related to the doping effect of the implant ed fluorine atoms.