Raman and Ellipsometry Study of Silicon-Containing Amorphous Hydrogenated Carbon
Abstract
The addition of Si to amorphous hydrogenated C (Si-AHC) films improves their durability while maintaining their desirable high-hardness, low-friction, and low-wear characteristics. The effects of added Si on the microstructure of Si-AHC films grown by a plasma-enhanced CVD process were studied using Raman scattering and spectroscopic ellipsometry. The relative intensity of D-band to G-band observed in Raman spectra of a-C reflects the average size of sp^2 clusters as well as the sp^2/sp^3 carbon bonding ratio. Using this metric for the Si-AHC films we find that both the sp^2 cluster size and the sp^2/sp^3 C-bonding ratio decrease with added Si. Lorentz parameters derived from a fit to the ellipsometric measurements provide additional information concerning the size distribution of sp^2 clusters, as reflected in the width of the π-π^* electronic transition. This width decreases as Si is added to the Si-AHC films, suggesting there is a narrower sp^2 cluster size distribution. The Si incorporation breaks down large sized sp^2 C clusters and enhances sp^3 bonding. The reduction of large sp^2 graphitic defects, the enhancement of sp^3 bonding, and the associated microstructure changes are responsible for the desired properties of Si-AHC.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 1998
- Bibcode:
- 1998APS..MAR.E1512Z