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The pure oxygen was introduced into the growth environment of the single crystal diamond with different contents, and the growth characteristics of single crystal diamond and the reaction dynamics in the plasma were studied in detail. As the ratio of O 2 to H 2 is up to 1.5%, the unique shaped etching pits with eight symmetric crystallographic planes appear. Optical emission spectra present typical characteristic radicals in the O 2 incorporated growth environment. With amount of O 2 increases, the growth rate decreases gradually due to the low active carbon source concentration and electron temperature. In the carbon contained hydrogen plasma, O 2 will react with CH radicals preferentially at low concentration and the dynamic equilibrium of CH and C 2 radicals was achieved at the O 2 concentration of 0.5% and 1%. Accompanying with the O 2 addition, the nitrogen and silicon related impurities have been reduced during the epitaxial growth process. Meanwhile, all of the FWHM of characteristic peaks in Raman decrease obviously after the epitaxial growth without and with O 2 addition, and FWHM of most samples are about 2.6 cm −1 , which are comparable with the natural type IIa SCD without stress. [ABSTRACT FROM AUTHOR]

In the present investigation, a nitrogen-doped multilayer homoepitaxial single crystal diamond is synthesized on a high-pressure high temperature (HPHT) Ib-type diamond substrate using the microwave plasma chemical vapor deposition (MPCVD) method. When 0.15 sccm of nitrogen was added in the gas phase, the growth rate of the doped layer was about 1.7 times that of the buffer layer, and large conical and pyramidal features are formed on the surface of the sample. Raman mapping and photoluminescence imaging of the polished cross sectional slice shows a broadband emission, with a characteristic zero phonon line (ZPL) at 575 nm in the doped layers, and large compressive stress was formed in the nitrogen-doped layers. X-ray topography shows that the defects at the interface can induce dislocation. The pyramid feature is formed at the defect, and more nitrogen-related defects are formed in the pyramid region. Thin nitrogen-doped multilayers were successfully prepared, and the thickness of the nitrogen-doped and buffer layers was about 650 nm each. The indentation measurements reveal that the thin nitrogen-doped multilayers are ultra-tough (at least ~22 MPa m1/2), compared to the Ib-type HPHT seed substrate (~8 MPa m1/2) and the unintentionally doped chemical vapor deposition (CVD) single crystal diamond (~14 MPa m1/2). [ABSTRACT FROM AUTHOR]