Technics Explore Of Synthesize Single-crystal Diamond By Chemical Vapor Deposition

Diamond is the hardest mineral in nature. And chemical stability, high thermal conductivity, high wear resistance and low coefficient of friction are all its excellent performances. And none property of any material can be compared with these properties. Diamond play an irreplaceable role in many industrial sectors, however, less natural diamond reserves, mining is difficult that make the diamond can not meet industry's needs.Chemical vapor deposition (CVD) method refers to a lower temperature and pressure conditions, homoepitaxial growth of single crystal diamond crystal. The method is simple and low cost, and large single crystal diamond particles of high-quality can be grown in a few days, and this approach can control appearance and geometry of diamond to make the diamond fully used.This article based on the research at home and abroad, and focused on a single crystal diamond MPCVD technical characteristic, and analyzed the deposition course of MPCVD and the growth mechanism of the single crystal diamond. During the experiment, we continuously improved experimental conditions (including temperature, pressure and the amount of hydrogen and methane, etc.), and recorded the growth of different test conditions and process, and statistical data for each test. At the same time, we test the synthetic crystals with infrared spectra, high power microscope, Raman spectroscopy etc. to determine the structure of crystal growth, and growth characteristics of the samples; eventually we find the best deposition parameters. The progresses we made and understand are as following:1. Through different experiments, we find the best ingle crystal diamond deposition parameters of MPCVD. What we made is useful to create the conditions for future researchers to provide a theoretical basis and experimental parameters.2. During the experimental course, we reveals the flow of hydrogen and nitrogen, flow of methane over saturation, and surface temperature and other parameters of crystal synthesis on the growth rate and quality of the law of deposition diamond crystal. It creates conditions to get the high purified, high-quality single crystal diamond.3. The deposition single crystal diamond with MPCVD and the crystal habit and crystal states have been studied. The single crystals are mainly composed of cube, octahedron, octahedron and rhombic dodecahedron, while the crystals form are mainly correlation with super-saturation of methane and the crystal surface of the crystal seed. The crystal grows mainly the form of step flow, and shows the paralleled and layered growth pattern.4. MPCVD single crystal diamond deposition process can be divided into two stages: nucleation and crystal growth.