3 - Diamond CVD Techniques

Abstract

This chapter explores the diamond chemical vapor deposition (CVD) techniques. A large variety of carbon-containing gas species have been employed to synthesize diamond by CVD. These include methane, aliphatic and aromatic hydrocarbons, alcohols, ketones, amines, ethers, and carbon monoxide with methane being the most frequently used reagent. In addition to these carbon carriers, the gas phase must usually contain powerful non-diamond carbon etchants and surface site preparation species such as hydrogen, oxygen, or fluorine atoms. The necessary condition for diamond growth is the presence of gas-phase non-equilibrium in the region adjacent to the deposition substrate. The gas-phase non-equilibrium is generated through gas-phase activation. The gas-phase activation is achieved typically using one of the three basic methods such as external heating (as in hot-filament CVD), plasma activation (as in plasma assisted CVD), a combination of thermal and chemical activation (as in flame CVD). Laser-enhanced CVD has also been applied to synthesize diamond. The advantages and disadvantages of the diamond CVD techniques and technical data are also summarized.