摘要
A plasma beam scanning treatment has been developed to modify the surface of the hydrogenated amorphous carbon (a - C:H) film on the indium tin oxide glass. The plasma beam scanning treatment makes the a - C:H film an excellent layer for liquid-crystal alignment. The qualities of a - C:H films were characterized by using atomic force microscope, micro-Raman spectroscopy, and field-emission scanning electron microscope. The ultrathin a - C:H films were deposited at 50% CH4 (H2 + CH4) gas ratio, 100 W radio-frequency power, and a gas pressure of 10 mtorr for 15 min by capacitive-coupled plasma chemical-vapor deposition method. The twist nematic cells were filled with liquid crystal (ZLI-2293) on the a - C:H film treated with different nitrogen plasma beam scanning time. The grooving mechanism is considered not responsible for the liquid-crystal (LC) alignment. Raman spectra suggest that a bond-breaking process of aromatic rings occurs in the a - C:H film. The O1s, C1s, and N1s core-level spectra support that the nitrogen plasma beam scanning treatment induces a bond-breaking process of aromatic rings to create available carbon dangling bonds for the formation of C-O bonds. The newly formed C-O bonds are "directional," which favor the LC alignment on the a - C:H film. © 2005 American Institute of Physics.