Characterizing growth conditions in chlorine-activated diamond chemical vapor deposition
Badgwell, Thomas A.
Doctor of Philosophy
This research expands the current scope of understanding on the chemical and engineering phenomena underlying chlorine-activated chemical vapor deposition (CACVD) of thin diamond films. Numerical modelling at various levels of sophistication results in good trend and reasonable magnitude agreement between numerical and experimental data. Modelling suggests a low substrate temperature diamond growth mechanism by atomic carbon insertion reactions. Such a mechanism becomes pronounced at high atomic hydrogen concentrations and can lower the apparent growth activation energy in the low substrate temperature regime. Experiments using tubular substrates with opposing Ar/Cl and CH4/H2 flows produced a variety of results, from isolated crystals to large areas of continuous diamond film. Spatial micro-Raman spectroscopy analysis indicates a large difference in diamond quality depending on the operating conditions used. Experiments indicate a much smaller operating region for diamond growth than obtained using a previous design by Pan et al. . Flat substrates with opposing flows produced better results than the tubular substrates.
Physical chemistry; Chemical engineering; Engineering; Materials science