Characterization of filament-assisted chemical vapor deposition diamond films using Raman spectroscopy

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Abstract
Results are presented on a Raman study of diamond films prepared by the filament‐assisted chemical vapor deposition technique from a methane‐hydrogen gas mixture. It is shown that Raman spectroscopy is a useful probe of both the phase of carbon present and of the quality of the diamond component in the films. The study entailed varying the total gas pressure, but holding the ratio of CH4 to H2 constant. It is clearly demonstrated that as the pressure is decreased, the density of defects within the diamond phase increases. The increase in defect density as the pressure is lowered leads eventually to disordered forms of carbon. This result can be understood in terms of the relatively higher electron and ion fluxes at the substrate for films prepared at low pressure.