| Abstract: | The effects of different surface pretreatment methods on the nucleation and growth of ultra-nanocrystalline diamond(UNCD) films grown from focused microwave Ar/CH_4/H_2(argonrich) plasma were systematically studied.The surface roughness,nucleation density,microstructure,and crystallinity of the obtained UNCD films were characterized by atomic force microscope(AFM),scanning electron microscopy(SEM),X-ray diffraction(XRD),and Raman spectroscopy.The results indicate that the nucleation enhancement was found to be sensitive to the different surface pretreatment methods,and a higher initial nucleation density leads to highly smooth UNCD films.When the silicon substrate was pretreated by a two-step method,i.e.,plasma treatment followed by ultrasonic vibration with diamond nanopowder,the grain size of the UNCD films was greatly decreased:about 7.5 nm can be achieved.In addition,the grain size of UNCD films depends on the substrate pretreatment methods and roughness,which indicates that the surface of substrate profile has a "genetic characteristic". |
