Effects of Oxygen on Diamond Growth

Abstract

In situ mass spectral measurements of the gas composition at the substrate surface were made during filament-assisted diamond growth. The input gases were various mixtures of CH 4 , 02, and H 2 chosen in order to discern the effects of oxygen addition on diamond formation and growth. The gas phase chemistry was modeled as a 1-dimensional flow reactor, and the measured and calculated species mole fractions were in good agreement. The model was then used to estimate mole fractions of several atomic and radical species which could not be measured. We fEnd that addition of 02 has only a small effect on the radical mole fractions. However, 02 can reduce the effective initial hydrocarbon mole fraction, which is important because higher quality diamond is grown at lower initial hydrocarbon mole fraction. Most importantly, perhaps, 02 addition leads to the formation of sufficient gas phase OH to remove non-diamond (pyrolytic) carbon from the film. Thus, 02 addition allows diamond films to be grown under composition and temperature conditions which otherwise would produce largely non-diamond carbon.

Effect of the admixture of N2to low pressure, low temperature H2-CH4-CO2microwave plasmas used for large area deposition of nanocrystalline diamond films

“…We note that the production of oxygen is very important in the diamond deposition process since it plays an essential role as an etching product of non-diamond phases [60] and abstraction of hydrogen atoms from surfaces [61].…”

Influence of pyrolysis parameters on the formation of an aerosol from ethane

“…Harris and Weiner 23 used scattering and extinction measurements to study the kinetics of soot inception in premixed ethylene/Ar/O 2 flames. They determined that small PAHs, such as naphthalene and acenaphthylene, as well as moderately sized PAHs, such as pyrene and coronene, did not contribute to the scattered signal.…”