Single crystal diamond produced by chemical vapor deposition (CVD) at very high growth rates (up to 150 m/h) has been successfully annealed without graphitization at temperatures up to 2200°C and pressures <300 torr. Crystals were annealed in a hydrogen environment by using microwave plasma techniques for periods of time ranging from a fraction of minute to a few hours. This low-pressure/high-temperature (LPHT) annealing enhances the optical properties of this high-growth rate CVD single crystal diamond. Significant decreases are observed in UV, visible, and infrared absorption and photoluminescence spectra. The decrease in optical absorption after the LPHT annealing arises from the changes in defect structure associated with hydrogen incorporation during CVD growth. There is a decrease in sharp line spectral features indicating a reduction in nitrogen-vacancy-hydrogen (NVH ؊ ) defects. These measurements indicate an increase in relative concentration of nitrogen-vacancy (NV) centers in nitrogencontaining LPHT-annealed diamond as compared with as-grown CVD material. The large overall changes in optical properties and the specific types of alterations in defect structure induced by this facile LPHT processing of high-growth rate single-crystal CVD diamond will be useful in the creation of diamond for a variety of scientific and technological applications. microwave plasma ͉ hydrogen ͉ vacancy ͉ nitrogen

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Abstract:We report on the first observation of stimulated Raman scattering (SRS) in single crystal diamond synthesized by chemical vapor deposition (CVD). An efficiency of 45% of energy conversion from the pumping Nd 3+ :Y 3 Al 5 O 12 laser radiation to all Stokes and anti-Stokes components is achieved. This makes single crystal CVD diamond an attractive χ (3) nonlinear crystalline material as a Raman laser converter.[111] a 0 F 2gThe cubic modification of natural and synthetic diamonds crystallizes in the O 7 h -space group with 8 C atoms per unit cell

Single crystals of diamond up to 18 mm in thickness have been grown by microwave plasma assisted chemical vapor deposition at gas pressures of up to 350 torr. Growth rates of up to 165 μm/h at 300 torr at high power density have been achieved. The processes were evaluated by optical emission spectroscopy. The high-quality single-crystal diamond grown at optimized conditions was characterized by UV-visible absorption and photoluminescence spectroscopy. The measurements reveal a direct relationship between residual absorption and nitrogen content in the gas chemistry. Fabrication of high quality single-crystal diamond at higher growth rates should be possible with improved reactor design that allows still higher gas synthesis pressures.