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

Abstract

Abstract Amorphous carbon-nitrogen films deposited by RF-magnetron sputtering onto Si substrates were annealed in vacuum in the temperature range of 300–800 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 ∼1360 cm−1 (D-band) and ∼ 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 ∼700 cm−1 (I700) and another at 2230 cm−1 (I2230). Normalized against the G-band, their intensities present opposite temperature dependence: I700 decreases by a factor of three, while I2230 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 bonds and of the size, or the number, of the graphitic domains.