A novel method was developed to deposit a large crystal diamond with good facets up to 1000μm on a tungsten substrate using a microwave plasma enhanced chemical vapor deposition (MPCVD).This method consists of two steps,namely single-crystal nucleation and growth. Prior to the fabrication of the well-faceted,large crystal diamond,an investigation was made into the nucleation and growth of the diamond which were affected by the O_2 concentration and substrate temperature.Deposited diamond crystals were characterized by scanning electron microscopy and micro-Raman spectroscopy.The results showed that the conditions of single-crystal nucleation were appropriate when the ratio of H_2/CH_4/O_2 was about 200/7.0/2.0,while the substrate temperature T_s of 1000℃to 1050℃was the appropriate range for single-crystal diamond growth.Under the optimum parameters,a well-faceted large crystal diamond was obtained.
