Structure of Diamond Films Grown Using High-Speed Flow of a Thermally Activated CH4-H2 Gas Mixture

Abstract

Diamond films are advanced engineering materials for various industrial applications requiring a coating material with extremely high thermal conductivity and low electrical conductivity. An approach for the synthesis of diamond films via high-speed jet deposition of thermally activated gas has been applied. In this method, spatially separated high-speed flows of methane and hydrogen were thermally activated, and methyl and hydrogen radicals were deposited on heated molybdenum substrates. The morphology and structure of three diamond films were studied, which were synthesized at a heating power of 900, 1700, or 1800 W, methane flow rate of 10 or 30 sccm, hydrogen flow rate of 1500 or 3500 sccm, and duration of the synthesis from 1.5 to 3 h.The morphology and electronic state of the carbon on the surface and in the bulk of the obtained films were analyzed by scanning electron microscopy, Raman scattering, X-ray photoelectron, and near-edge X-ray absorption fine structure spectroscopies. The diamond micro-crystals with a thick oxidized amorphous sp2-carbon coating were grown at a heating power of 900 W and a hydrogen flow rate of 1500 sccm. The quality of the crystals was improved, and the growth rate of the diamond film was increased seven times when the heating power was 1700–1800 W and the methane and hydrogen flow rates were 30 and 3500 sccm, respectively. Defective octahedral diamond crystals of 30 μm in size with a thin sp2-carbon surface layer were synthesized on a Mo substrate heated at 1273 K for 1.5 h. When the synthesis duration was doubled, and the substrate temperature was decreased to 1073 K, the denser film with rhombic-dodecahedron diamond crystals was grown. In this case, the thinnest hydrogenated sp2-carbon coating was detected on the surface of the diamond crystals.

Electronic Structure of Nitrogen- and Phosphorus-Doped Graphenes Grown by Chemical Vapor Deposition Method

“…Annealing of the films in an ultra-high vacuum at 773 K substantially reduces the amount of these bonding states. The termination of edge carbon atoms with hydrogen at a high content of H 2 in the reaction mixture is probably a common phenomenon [65]. Table 1.…”

Iron-Catalyzed Growth of Vertical Graphitic Layers on the (100) Face of Single-Crystal Diamond

“…Figure b presents the AEY NEXAFS C K-edge spectrum of clean diamond taken at an incidence angle of 45° in order to eliminate the anisotropy of the π*- and σ*-states from sp 2 -carbon species. Registration of Auger electrons with a kinetic energy of 260 eV allows probing the sample to a depth of ∼1 nm . The spectrum shows no the excitonic σ*-peak of diamond, while the low-energy π*-peak has a relative intensity higher than that observed in the TEY spectrum measured at 90° (Figure a).…”

Effect of Titanium and Molybdenum Cover on the Surface Restructuration of Diamond Single Crystal during Annealing

“…All spectra are dominated by the bulk sp 3 –carbon peak located at 286.0 eV. The tiny peak that appears at higher binding energies is assigned to oxygen-containing contaminations of the diamond surface [ 7 , 46 ]. There are two peaks shifted by ca.…”