45-degree rotated epitaxial nucleation of diamond on silicon using chemical vapor deposition

45-degree rotated epitaxial diamond nucleation on both (001) and {111} planes of a silicon substrate was observed using chemical vapor deposition with nucleation enhancement by electron emission. The epitaxial relationship between diamond and Si is D(001)//Si(001) and D<100>//Si<110> in both cases. While the case of diamond nucleation on Si(001) may be explained in Verwoerd's model, the other case has no theoretical model as yet. The as-grown diamond was characterized by scanning electron microscopy and Raman spectroscopy. It is speculated that a suitable combination of low temperature and low CH_4 concentration leading to low nucleation rate favors the 45-degree rotated epitaxy over those in parallel registry. This observation sheds light on the mechanism of epitaxy of diamond on Si substrates, and has great significance in parameter control in achieving single-crystal epitaxial diamond films.