RAMAN SCATTERING STUDIES ON THE STRUCTURAL PROPERTIES OF PULSED LASER DEPOSITED AMORPHOUS CARBON NITRIDE THIN FILMS

Raman scattering analysis revealed that the structure of carbon (C) films prepared by pulsed laser deposition at room temperature is predominantly amorphous and the structure of amorphous C nitride (a-CNx) films can be changed with varying substrate temperatures (ST) from 20 to 500°C. The deposited a-CNx films are composed of C–N, C≡N and C–O bonded materials and the C–N and C≡N bonds are increased with ST. We have found no other obvious peaks that can be distinguished in the range of 900 to 2300 cm-1 in which several peaks always appear in a-CNx films. The spectra were deconvoluted into Raman D and G peaks and the structural parameters were determined. The upward shifts of Raman G peak towards 1592 cm-1 show evidence of a progressive formation of crystallites in a-CNx films upon increase of ST, while the upward shifts of Raman D peak towards 1397 cm-1 have been related to the decrease of bond-angle disorder and sp3 tetrahedral bonding in its structure. Raman FWHM and ID/IG also indicate that N incorporation with increase of ST caused an increase in the number and/or size of graphitic domains in the a-CNx films.