Growth kinetics of (100), (110), and (111) homoepitaxial diamond films

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Abstract
We present the first investigation of the growth kinetics of diamond films grown homoepitaxially by hot-filament chemical vapor deposition on (100), (110), and (111) natural diamond substrates. Growth rates on the various faces exhibited different functional dependencies on CH4 flow rate, being linear on (100), slightly sublinear on (110), and sigmoidal on (111). The temperature dependence of the growth rate was also crystal-face-dependent, yielding effective activation energies of 8±3, 18±2, and 12±4 kcal/mol for [100], [110], and [111] growth, respectively, at substrate temperatures between 735 and 970 °C. The apparent activation energies were considerably larger at substrate temperatures between 675 and 735 °C. We propose that these crystal face and temperature effects are due principally to differences and changes in the nanometer-scale morphology and surface hydrogen coverage with methane concentration and surface temperature.