Abstract: Diamond films were prepared by an electron assisted chemical vapor deposition system (EA-CVD) in an atmosphere with a nitrogen addition.SEM,Raman spectroscopy,and EPR were employed to study the influence of nitrogen on the films’ quality and the characteristics of nitrogen doping.The results show that for the films deposited at 950℃,the morphology changes to cauliflower-like structures,the content of non-diamond carbon increases,and the quality drops after adding nitrogen into the atmosphere.For the films deposited at 800℃,the addition of nitrogen reduces the twins and secondary nucleation,and improves the films' morphology.EPR and Raman spectra indicate that nitrogen impurities in the films mainly exist in the forms of Ns0,［N-V］0,and ［N-V］-1.Along with the increase of nitrogen flow rate,the content of Ns0 increases,the content of ［N-V］0 decreases,and the content of ［N-V］-1 does not change obviously.

Key words: diamond film, EA-CVD, film quality, nitrogen impurity