The effect of surface roughness of seed on the high-rate homoepitaxial growth of CVD single-crystal diamonds

Although diamond seeds are generally polished before growth, the effect of surface roughness of diamond seeds on crystal growth quality is rarely studied. In this research, three diamond seeds were prepared for researching the effect of surface roughness of diamond seed. They were made by cutting a bulk diamond and subsequently suffered partially polished, totally polished and unpolished, respectively. After a period of microwave plasma chemical vapor deposition growth, various tests were carried out on the samples. According to the microscope and step profiler, the surface roughness of diamond seed did not affect the surface roughness of long-term growth diamonds. Compared by Raman spectra, ultraviolet − visible and infra-red spectra, it indicated that a certain rough surface of diamond seed could improve the internal stress of diamond, but reduce the crystalline quality slightly. Moreover, the surface roughness had almost no impact on the optical properties of the diamond. As a result, diamond seeds with low roughness after cutting could be used for direct growth without polishing, bringing on significant economic for gem-quality diamond production.