Microwave plasma chemical vapor deposition
Chemical vapor deposition CVD method to grow polycrystalline diamond film came out in the mid -1980 s. Single crystal CVD diamond began to be developed in the late 1990 s. By the early 2000 s, element 6. Carnegie, Apollo and other companies had successfully grown, but failed to form a market. At the beginning of 2012, Singapore's IIa Company commercialized colorless high-quality jewelry diamonds grown by microwave plasma chemical vapor deposition from small to carat grades. Its selling price is 1/3 to 1/2 lower than that of natural diamonds of the same grade, which shocked the natural diamond market. In fact, single crystal jewelry diamond is only a small part of the CVD function, a large area of 6-8 inch diameter polycrystalline diamond film in sound, chemical, light, heat, electricity, there are more and more important uses.
Principle of diamond growth by CVD
Hydrocarbons such as methane are dissociated by the high energy of plasma under gaseous conditions to generate atomic-level carbon ions deposited on the surface of a heated solid substrate, thereby producing polycrystalline or single crystal diamonds, known as chemical vapor deposition synthetic diamonds.
Plasma source: microwave; DC arc jet; hot wire; RF.
Seed Substrate: Natural, HPHT or CVD synthetic diamond is cut into thin slices parallel to the (100) crystal plane to grow single crystal diamonds.
Gas: H2,CH4,O2 or N2
Temperature: 700 - 1000°C
Vacuum degree: 1/10 atmospheric pressure
Growth efficiency: 1~50 microns/hour
Different energy sources for CVD equipment:
DC arc jet and hot wire method can only be used in polycrystalline low-end applications because of metal contamination. The RF mode is less efficient. At present, the more mature CVD technology in China is hot wire and DC arc plasma jet. The use of high-power microwave plasma technology equipment (equipment expensive, high operating costs) to produce CVD diamond has not yet been found in the relevant reports. The microwave mode is divided into two microwave frequencies of 2.45GHz and 0.915GHz. The latter can achieve a power of tens to 100 kilowatts KW, and its substrate diameter can reach 6-8 inches. Compared with the former, the quality and production efficiency are much higher, which is the future trend of CVD furnace.
To participate in the "2011 Beijing International Lighting Exhibition" exhibition held in Beijing
Participate in the "7th Guangzhou International LED Exhibition (LED CHINA 2011)" exhibition held in Guangzhou
To participate in the "Japan International Electronic Products Exhibition" held in Tokyo, Japan"
Participated in the "Twelfth China International High-tech Achievement Fair" held in Shenzhen and won the "Excellent Product Award" certificate
Dr. Yuan Zhizhong, Chairman of Bench Diamond Technology, gave a lecture entitled "Identification of Gem Diamonds Cultivated by CVD Method" at the Appraisal Institute on the 11.9 at the invitation of the Appraisal Institute of Taiwan Gemological Institute. In the lecture, Yuan Dong introduced in detail the historical principles of CVD diamonds and their development status, and introduced in detail several methods to distinguish CVD diamonds from natural diamonds on how to identify gem-grade CVD diamonds that participants are concerned about! Yuan Dong's wonderful speech was well received by the participants!
Dr. Yuan Zhizhong, Chairman of Bench Diamond Technology, was invited by Hangzhou International Jewelry City to attend an academic symposium on November 19, 2013. At the symposium, Yuan Dong gave a speech entitled "International Situation and Identification of CVD Synthetic Diamonds" on the current situation of CVD synthetic diamonds that jewelers are concerned about and how to distinguish CVD diamonds from natural diamonds. In the speech, Yuan Dong introduced in detail the history of CVD diamonds, the international situation of CVD diamonds and the commonly used identification methods of CVD diamonds, and answered some questions raised by jewelers. Mr. Yuen's speech was well received by the participants, and all jewelers said they benefited.