Preparation of electrically conductive diamond-like carbon films using i-C₄H₁₀/N₂ supermagnetron plasma

Electrically conductive diamond-like carbon (DLC) films were deposited by supermagnetron plasma chemical vapor deposition. The deposition was made on Si and glass wafers using mixed isobutane (i-C₄H₁₀) and N₂ gases. The physical properties of deposited film were measured and analyzed. Fourier transform infrared spectroscopy measurements revealed that the absorption due to N–H, C–N, and CN bonds increased with increases in N₂ gas concentration. The increase in electrical conductivity could be attributed to C–N and CN bond creation in the DLC films. The lowest resistivity, 0.17 Ω cm, was achieved at an N₂ concentration of 70%, gas pressure of 50 mTorr, lower electrode temperature of 160 °C, and rf powers of 1 kW/1 kW. The lowest resistivity film was 1750 kg/mm² hard, harder than glass (1340 kg/mm²). Raman spectroscopy measurements revealed two peak D and G bands, and the D band was more intense than the G band. The optical band gap decreased with increases in the N₂ concentration. Hall measurements showed that the carrier was n type and both carrier density and Hall mobility increased with rf powers. © 2001 American Institute of Physics.