Nanocrystalline Diamond Films Deposited by Microwave Plasma CVD in Mixtures of Argon and Methane with and without Hydrogen Additive

Nanocrystalline diamond films were deposited on silicon by microwave plasmas in gas mixtures of 1% CH4 + 99% Ar, and 1% CH4 + 5% H2 + 94% Ar. Raman scattering, average surface roughness, surface morphology, and electron field emission characteristics were examined and correlated. Nanodiamond films with average roughness of five to fifteen nanometers were deposited. Very smooth nanodiamond films have been deposited. Electron field emission currents from these nanodiamond films were very low even at an applied electric field of 20 V/μm. Nanodiamond films deposited at a high gas pressure of 200 torr without hydrogen additive were found to emit a higher electron current than other nanodiamond specimens deposited at lower gas pressures or deposited in plasmas with hydrogen additive. Surface roughness including micron and submicron sized particles on the surface of the nanodiamond contributed to the higher electron field emission current. Smooth and micron sized particle-free nanodiamond films deposited in hydrogen-poor plasmas exhibited very small electron field emission current.