Influence of CH4 on the morphology of nanocrystalline diamond films deposited by Ar rich microwave plasma

The influences of the process gases, such as methane and nitrogen concentration on the morphology of nanocrystallites diamond films are assessed. It has been found that the concentration of CH4 in the reactant gases is important to control the morphology of diamond nanocrystallites. The morphology of nanocrystallites changes from granular to rodlike shape by changing methane concentration in Ar/H2/CH4 microwave plasma. The addition of nitrogen is considered to be helpful in the formation of graphite content and for increasing the deposition rate. No considerable changes in the morphology of diamond nanocrystallites were observed by varying nitrogen concentration in the feed gases as observed by scanning electron microscopy. Although Raman spectroscopy indicated that the amount of sp2-bonded carbon increased by the addition of nitrogen in the plasma. The high concentration of methane in the gas mixture due to the presence of argon rich environment is suggested to be responsible for the formation of diamond nanorods.