In a laboratory-made 10 kW microwave plasma chemical vapor deposition (MPCVD) apparatus

the influence of methane concentration on the growth of diamond film under a high-power microwave plasma was analyzed. The characteristics of high-power microwave plasma discharge environment were diagnosed by plasma emission spectroscopy. At the same time

the morphology and quality of diamond films obtained under different deposition conditions were characterized by SEM and Raman spectroscopy to determine diamonds in a highpower microwave plasma environment. The optimal methane concentration range for membrane growth was abtained. Experiments show that when microwave power is kept at 5000 W

when the CH4/H2 is less than 1%

the secondary nucleation phenomenon in the diamond film is obvious

and the grain size is small; when the CH4/H2 is more than 2.5%

the diamond film can get larger crystal grains

but easy to produce germanium crystals; when CH4/H2=1.5%-2%

diamond films with complete crystal grains and high quality can be obtained.