In-Situ Diagnostics of Diamond CVD

The deposition of diamond, a metastable crystalline form of carbon, from low pressure gases poses intriguing questions about the mechanisms of growth. Tunable IR Diode Laser Absorption Spectroscopy, Laser Multi-Photon Ionization Spectroscopy, and Laser Induced Fluorescence were used to characterize the gaseous environment in the Chemical Vapor Deposition growth of diamond films. The quality of the deposited material was examined by optical and SEM microscopies, and Raman, Auger, and XPS spectroscopies. When a reactant mixture of 0.5% methane in hydrogen, was passed across a hot Tungsten filament (2000 C), C2H2, C2H4, H and CH3 were detected above the growing diamond surface, and concentration limits for undetected species were determined. These results are discussed in terms of simple models for species formation and consumption, as well as the implications for the diamond growth mechanism.