Hydrogen release from a-C/H films by MeV irradiation

Amorphous hydrogenated hard carbon films deposited on silicon substrates from a rf-benzene plasma were irradiated with helium, nitrogen, neon and argon ions in the MeV range. The ion passage through the material leads to a break of C-H bonds followed by a release of hydrogen. The hydrogen contert of the films were measured before and after irradiation using the nuclear resonance reaction high 1 H(high 15 N, alpha gamma) high 12 C. The experimental results show that the amount of hydrogen loss is related to the electronic stopping and the ion fluence. The decrease in hydrogen content under high 15 N ion bombardment as a function of the ion fluence yields a curve which can be decomposed into three exponential decays corresponding to effective cross sections in the range of 10 high 15 cm high 2 to 10 high minus 17 qcm.