Oxidation Effects on Polycrystalline Diamond Film Surface

Polycrystalline diamond films deposited by Hot Filament CVD technique are oxidized in both Thermogravimetric Analyser (TGA) and Lindberg furnace at temperature from 500°C to 800°C. TGA result shows that the onset oxidation temperature is about 700°C and the activation energy is 175kJ/mol. SEM images indicate that {111} facets are preferentially oxidized, {100} is the least reactive facets. On {111} facts, the oxidation is not randomly but regularly oriented, with some thin and long ridges parallel to <110> direction, which has not been reported before. After oxidation at 700°C and 800°C, slight graphitization on diamond surface is indicated by Raman spectra.