F2, H2O, and O2 etching rates of diamond and the effects of F2, HF and H2O on the molecular O2 etching of (110) diamond |
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Authors: | C J Chu C Pan J L Margrave R H Hauge |
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Affiliation: | Rice University, Department of Chemistry, Houston, Texas 77251, USA |
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Abstract: | Oxidation kinetics of natural (110) diamond by oxygen and water were investigated using in situ Fizeau interferometry. Apparent activation energies of 53 and 26 kcal mol?1 were obtained for the etching of (110) type Ia diamond by O2 and H2O respectively. The etch rate was found to follow second-order kinetics with respect to O2 pressure in the pressure range 0.04–10 Torr. For water over the vapour pressure range 0.1–2 Torr, the reaction has a reaction order near unity. The diamond (110) surface was impervious to etching by molecular fluorine at all temperatures up to 1300 °C. Fluorine, hydrogen fluoride and water were found to inhibit the molecular oxygen etching of diamond. Below 900 °C, oxidation is inhibited by the addition of F2 and HF presumably by blocking reactive sites on the diamond surface through formation of C---F bonds. Above 900 °C, the fluorine is thought to desorb from the diamond (110) surface, rendering the surface susceptible to further oxidation. Addition of water below 800 °C was found to retard etching by molecular oxygen. This is attributed to the formation of C---OH bonds, analogous to C---F. |
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Keywords: | Diamond Etching Fluorine Oxygen |
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