Raman spectroscopy of annealed carbon nitride films deposited by RF-magnetron sputtering

Amorphous carbon-nitrogen films deposited by RF-magnetron sputtering onto Si substrates were annealed in vacuum in the temperature range of 300-800 degrees C during 30 min, with no sequential treatment. The films were analyzed by Raman spectroscopy, used as a probe of microstructural modifications induced by thermal treatment. The main features observed in the Raman spectra are two broad bands at similar to 1360 cm(-1) (D-band) and similar to 1575 cm(-1) (G-band), characteristic of amorphous carbon materials. The ratio between their intensities (I-D/I-G) is found to increases with the annealing temperature. Additionally, the spectra present other two weak bands, one at similar to 700 cm(-1) (I-700) and another at 2230 cm(-1) (I-2230). Normalized against the G-band, their intensities present opposite temperature dependence: I-700 decreases by a factor of three, while I-2230 increases by the same factor in the temperature range studied here. A strong reduction of the luminescence background with the annealing temperature is observed. These results indicate a substantial reduction of the dangling bonds accompanied by an increase of the number of C=N bends and of the size, or the number, of the graphitic domains. (C) 1998 Elsevier Science S.A.