| Abstrakt: |
Addition of di-nitrogen to the feed gas has been shown to greatly influence growth rates and morphology of the deposited layer in various diamond chemical vapor deposition (CVD) techniques. In this article, several hypotheses for these phenomena, as presented in literature, are tested for the case of diamond combustion CVD with the aid of an atmospheric pressure oxyacetylene flame. For this purpose, one-dimensional and two-dimensional simulations are performed of the hydrodynamics, the combustion and deposition chemistry, and the nitrogen chemistry. Based on the simulation results, several proposed hypotheses can be ruled out as possible explanations for the observed phenomena. It is concluded, that the most likely hypotheses are: (i) the presence of nitrogen atoms in the diamond lattice, enhancing diamond growth by acting on the electron structure of surface dimer bonds, and (ii) selective adsorption of nitrogen-containing species on the surface, selectively increasing growth in the (100) direction. It is found that possible gas phase candidates for affecting diamond growth are NH, NH[sub 2], NH[sub 3], CN, HCN, H[sub 2]CN, and NCO. [ABSTRACT FROM AUTHOR] |
