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The a-C:H films were grown on the soda-lime glass substrates by using the DC-FTS method. The effects of the CH4 gas and substrate temperature on the deposition rate and properties of the film were investigated. The deposition rate of the film grown under the Ar-CH4 plasma was found to be three times larger than that of the film under the Ar plasma. The deposition rate of the film was also found to be linearly dependent on the substrate temperature. This increase in the deposition rate can be attributed to the CH* radical arising from the addition of CH4 gas during the deposition process. The above findings were confirmed by the optical emission, Raman, and XPS spectra. In the Raman spectra, the intensity of the G peak representing the C=C chain group increased with increasing substrate temperatures, while XPS revealed that the sp3 fraction in the film increased with increasing substrate temperatures. Similarly, the optical transmittance revealed a gradual increase in the optical band-gap energy with increasing substrate temperature. This substrate temperature dependence of the band-gap energy can be attributed to the increase in the fraction of sp3 bonding with increasing substrate temperatures, which agrees with the results of the XPS analysis. We also found that the infrared transmittance of the a-C:H film grown under the Ar-CH4 plasma was much larger than that of the film grown under the Ar plasma. Overall, the results of this study indicate that the deposition rate of the a-C:H film was enhanced by adding CH4 gas during deposition and by increasing the substrate temperature. This occurred in response to the CH4 plasma which changed the deposition process from physical to reactive deposition. The sp3 fraction in the film was found to increase with substrate temperatures, which influenced the band-gap energy and consequently the transmittance of the film.
The TiN films were deposited onto the soda-lime glass substrates by using the DC-FTS method, and the effects of N2 flow rate on the film properties were investigated systematically. The deposition of the film was performed at a relatively low temperature (150oC). The TiN films exhibited gold-like color, very low resistivity (∼ 30μΩ·cm), and rock salt structure. As the N2 flow rate increased, the preferred orientation of the films changed from the (111) to (200) plane. The change in the growth orientation was due to the competition between the surface and strain energies in the films, which is strongly related to the kinetic energy of incident particles onto the substrate. Also the N2 flow rate affected the kinetic energy loss due to the change in the inner degree of the freedom of molecular gases. The DC-FTS can be used to deposit TiN films onto flexible substrates because of its relatively lower deposition temperature.
The characteristic of the magnetized plasma were investigated to apply it to the damage- free surface treatments. The surface treatments of the PES(Polyethersulfone) films were performed by using the magnetized plasma. The contact angle between the water droplet and the PES film was observed to change from 80° to 30° after the plasma treatment. This indicates that the surface properties of the PES film were changed from hydrophilic to hydrophobic. The surface roughness of the films was not changed after plasma treatment and this indicates that the magnetized plasma did not damage the surface of the film. The trap of the energetic particles by magnetic field is thought to be responsible for this result. It is concluded that the plasma treatment by using the magnetized plasma id useful for the surface modification of the polymeric materials.
Thesis Advisor: Prof. Ilsu Rhee