Density functional simulations of silicon-containing point defects in diamond

Silicon impurities in diamond lead to the appearance of the well known system of 12 lines around 1.681 eV, thought to arise from the silicon-vacancy complex. This system is produced by various treatments suggestive of other silicon-related centers in the material. In order to elucidate possible structures of Si in diamond, we have performed first-principles calculations. We show that interstitial Si is unstable at growth temperatures, substitutional Si is most likely visible only by vibrational mode spectroscopy, and complexes of silicon with lattice vacancies are electrically, paramagnetically, and optically active. In addition, we report on Si-N and Si-H complexes in the context of doping and the KUL3 electron paramagnetic resonance center, respectively.