Abstract: Thick diamond films have been deposited by Electron Assisted Hot Filament Chemical Vapor Deposition Method. The effects of hydrogen gas flow rate on the diamond films growth rate and diamond qualities have been studied. It is found that, with the gas flow rate increasing, in the range of 100 to 750 cm³/min, the diamond films growth rates increase while the diamond qualities get worse, and in the range of 750 to 1000 cm³/min the diamond films growth rates decrease whilethe diamond qualities are improved. Raman spectroscopy and Electron Paramagnetic Resonance has been used to detect the impurities of Nitrogen. The concentration of nitrogen in the diamond film decreases with the increase of gas flow rate, and it is 40 times higher in diamond films deposited at 100 cm³/min than that at 1000 cm³/min.

Key words: Diamond films, Paramagnetic nitrogen, Electron paramagnetic resonance