Raman spectroscopy of a-C:H:N films deposited using ECR-CVD with mixed gas

Ultraviolet (UV) and visible Raman spectroscopy were used to study a-C:H:N films deposited using ECR-CVD with a mixed gas of CH4 and N2. Small percentage of nitrogen from 0 to 15% is selected. Raman spectra show that CN bonds can be directly observed at 2220cm-1 from the spectra of visible and UV Raman. UV Raman enhances the sp1 CN peak than visible Raman. In addition, the UV Raman spectra can reveal the presence of the sp3 sites. For a direct correlation of the Raman parameter with the N content, we introduced the G peak dispersion by combining the visible and UV Raman. The G peak dispersion is directly relative to the disorder of the sp2 sites. It shows the a-C:H:N films with higher N content will induce more ordered sp2 sites. In addition, upper shift of T position at 244nm excitation with the high N content shows the increment of sp2 fraction of films. That means the films with high N content will become soft and contain less internal stress. Hardness test of films also confirmed that more N content is with less hardness.