Preparation And Properties Of CVD Hemispherical Diamond Films And Single Crystal Diamonds

Diamond is an important semiconductor which has many excellent properties in the applications. In this article, high-quality large size single-crystal diamond and TiO2nanotubes/hemispherical polycrystalline diamond were synthesized by MPCVD, and the corresponding mechanism is discussed. The details of our work are as follows:Several parameters that affect the growth of were analyzed, such as the carbon concentration (methane concentration), microwave power and the pressure. Especially discuss the influence of subtract materials of diamond. High quantity and transparent hemispherical diamond film was prepared on the most optimize condition.1,In the deposition process, the carbon concentration (methane concentration) greatly affect the growth of diamond films. The growth rate of the diamond film increased as the methane concentrations increases, but as a result, the quality declines. Microwave power and pressure are other factors that affect the film growth characteristics. It directly influences the shape and energy density of the plasma glow. The growth rate increases as the power increase. The overwritten area of substrate increases, thus uniformity of hemispherical diamond gets better.2,In the MPCVD deposition process, the substrate materials greatly influence on the growth quality of diamond film. We prefer Mo as the substrate of hemispherical diamond, and prepare quality transparent diamond film. The hemispherical diamond is prepared by MPCVD, and then the ZnO nanorods (NRs) have been hydrothermally synthesized with a ZnO buffer layer. The TiO2nanotubes/hemispherical diamond have been prepared by the liquid-phase deposition (LPD) method and the photocatalytic properties have been studied. The results are obtained as follows:1,ZnO NRs were fabricated with the solution of hexamethylenetetramine (HMT, C6H12N4) and zinc nitrate hexahydrate (Zn(CH3COO)2·2H2O) on the hemispherical diamond.2,The fabrication of TiO2nanotubes were achieved using ZnO NRs as template with the proper concentration of ammonium hexafluorotitanate ((NH4)2TiF6) and boric acid (H3BO3) by LPD method.3,The TiO2nanotubes/hemispherical diamond show enhanced photocatalytic activities.The effect of N2, O2, CO2and N2O during the single-crystal diamond growth progress has been discussed, and high quality transparent single-crystal diamond has been prepared.1,During the progress of single-crystal diamond with CH4/H2/N2atmosphere, the ratio of N2and O2can influence the growth rate and morphology. Especially for the gowth rate of diamond can be increased as rate of N2and O2enhanced. When the flow of N2gets to4sccm, the growth rate will be reduced as the N2increased.2,It comes to the conclusion that the growth rate is increased at first, and reduced afterwards while CO2increased. The morphologies of single-crystal diamond are obvious changed with different flow of CO2.3,In the single-crystal diamond growth process, the rate of growth can reach135μm/h with introduce the N2O, N and O, thus assure high quality with rapid growth rate.4,We developed CVD single-crystal diamond cutter using for the curved mirror face polishing of metallic material. High quantity and transparent films were prepared with the most optimize condition. The applications of single-crystal diamond have extensity development in the diamond films.