The formation of new phase and chemical bonds in N-doped diamond films induced by swift heavy ion irradiation

In this paper, the formation of the new phase and chemical bonds in N-doped diamond films after swift heavy ion irradiations was studied. The original samples were diamond films grown on (1 1 1) oriented p-Si by CVD deposition. These samples were implanted with 100 keV N-ions at room temperature to 5 × 10 17 , 1 × 10 18 and 5 × 10 18 N/cm 2 , irradiated with 345 MeV Xe or 2.64 GeV U ions, and then analyzed by means of RBS, micro-FTIR, micro-Raman and XRD spectroscopy. The obtained results suggested that N-sp 2 C and N-sp 3 C bonds formed in all N-doped diamond films, CN bond exists in all 5 × 10 18 N/cm 2 doped samples but could not form in the 5 × 10 17 N/cm 2 doped samples. In the 1 × 10 18 N/cm 2 doped sample, CN bond could form only after swift heavy ion irradiation. Intense energy deposition from the incident swift heavy ions induces the increase of sp 3 /sp 2 bonding ratio and thus enhances the formation of N-sp 3 C bonds in the samples. Furthermore, the X-ray diffraction analysis indicated that there existed new phases, α- and β-C 3 N 4 in the N-doped diamond samples after irradiation by swift heavy ions.