Development of the microwave plasma CVD technique for rapid growth of large single-crystal diamond

Summary form only given. The method of high growth rate single crystal microwave plasma chemical vapor deposition (CVD) diamond has opened new applications for precision tools, electronics, optics, and consumer gems. Here we provide an overview of techniques developed under a Carnegie Institution program for producing large single crystal CVD diamond (>1 cm thick, 10 carats) at very high growth rates of ~100 m/h. These diamonds exceed the sizes of those of commercially available crystals made by high-pressure/high-temperature (HPHT) methods. The various microwave plasma CVD systems we have used include home-made, window and bell-jar type reactors. In order to achieve higher growth rate, the energetic plasma was produced at higher methane concentration 8-20% CH₄/H₂, and higher pressure 160-220 torr at various temperature 900-1400degC. Substrates were HPHT synthetic type Ib yellow or single crystal CVD diamonds with {100} faces on all sides. Morphologies and colors of the as-grown CVD diamonds strongly depend on the deposition temperature and pressures at various systems. Using the above conditions, gem-quality CVD diamond can be grown individually and sequentially on the 6 {100} faces of the substrate. The prospects for producing much larger single crystal diamond with next generation reactors will be discussed