Structure of nitrogenated carbon films prepared from acetylene and nitrogen mixture in electron cyclotron resonance plasma

Amorphous nitrogenated carbon (a-CNx) films have been prepared from a mixture of acetylene and nitrogen gas in an electron cyclotron resonance plasma and characterized by electron energy-loss spectroscopy (EELS), spectroscopic ellipsometry (SE), Fourier transformed infrared (FTIR) spectroscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, and ultraviolet photoelectron spectroscopy. From EELS and SE, a significant change in the pi plasmon peak position and a reduction of its area is observed in the carbon films after nitrogen introduction, which suggest that there is no further development of graphitic structure. The features of D and G peaks observed from Raman as well as FTIR spectra support a decrease in the amount of sp(2) bonded carbon in the a-CNx films. Valence band spectra using He I and He II excitations show that the p-pi band becomes less intense upon nitrogen addition. A comparative study between the characteristics of these films and the films deposited from a methane-nitrogen mixture using an identical procedure is also presented. It is found that the structural changes in these films upon nitrogen incorporation are different, indicating a definite role of the precursors on the film structure. (C) 2000 American Institute of Physics. [S0021-8979(00)04809-X].