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

摘要

Ultraviolet (UV) and visible Raman spectroscopy were used to study a-C:H:N films deposited using ECR-CVD with a mixed gas of CH_4 and N_2. Small percentage of nitrogen from 0 to 15% is selected. Raman spectra show that C≡N bonds can be directly observed at 2220 cm~(-1) from the spectra of visible and UV Raman. UV Raman enhances the sp~1 CN peak than visible Raman. In addition, the UV Raman spectra can reveal the presence of the sp~3 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 sp~2 sites. It shows the a-C:H:N films with higher N content will induce more ordered sp~2 sites. In addition, upper shift of T position at 244 nm excitation with the high N content shows the increment of sp~2 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.