Modeling CVD diamond with density functional theory

Chemical vapor deposition (CVD) of polycrystalline films of diamond has improved dramatically during the past six years. During this time there have been parallel developments in modeling chemical processes at a diamond surface, with many of the first-principle studies being carried out within the density functional framework. We review our work on furthering the understanding of chemical processes that may be important in the growth process, which requires knowledge of first, the surfaces themselves and second, adsorption of hydrocarbon radicals to add more layers. Studies of both clean and hydrogenated (111), (100), and (110) surfaces of diamond show that clean surfaces tend to undergo strong relaxation and reconstruction while hydrogenation results in inert surfaces. Modeling interactions of various hydrocarbon radicals with diamond surfaces provides energies and geometries of viable processes while eliminating from further consideration processes that are found to be unfavorable. We also discuss briefly recent investigation of behavior at a step on a clean diamond surface, which may indicate a process leading to graphitization of the diamond surface.