Phase control of N-type nanocrystalline diamond films deposited in microwave plasmas from methane and acetylene

Summary form only given. Nanocrystalline diamond (NCD) film is a novel form of artificial diamond grown from highly fragmented hydrocarbons by using plasmas. The films are the composite of nanodiamond particles and amorphous carbon matrix. One of the unique properties of NCD films is n-type conductivity. In this study, the amount and composition of amorphous nondiamond phases in NCD films deposited from moderate or low-pressure microwave plasmas from CH₄ and C₂H₂ are examined to obtain a clue to phase-pure NCD films. Also, the electrical properties of nitrogen-doped films are examined to demonstrate semiconductor properties. Visible Raman spectroscopy for NCD films with average crystallite sizes below 25 nm revealed that the amount of amorphous carbon corresponding to the D peak intensity was reduced and consequently the diamond peak was clearly observed when C₂H₂ was used. The electrical properties of nitrogen-doped NCD films were also examined and discussed along microstructures and phase composition of the films