AB-INITIO ENERGETICS OF CVD GROWTH REACTIONS ON THE 3 LOW-INDEX SURFACES OF DIAMOND

Two novel CVD diamond growth mechanisms arc proposed which involve met hyl radicals and acetylene molecules where carbon atoms are inserted i nto {100} 2 x 1 monohydride dimer surface reconstruction bonds. We hav e built models of the three principal surfaces of diamond and performe d ab initio local density-based calculations to determine structures a nd energies or surface reactions including the two postulated for 2 x 1 reconstructed {100}. Both of these processes are found to be exother mic but with large barriers. However, they do demonstrate that reconst ruction bonds can facilitate growth. The results are discussed with re spect to the large body of recent experimental results and we conclude that the relative contributions of methyl and acetylene depend on the system used.