Defect characteristics in sulfur-implanted CVD homoepitaxial diamond

Characteristics of defects in diamond single crystals grown by chemical vapor deposition associated with sulfur ion implantation were investigated by cathodoluminescence (CL), particle induced X-ray emission (PIXE) with ion channeling, and secondary ion mass spectrometry (SIMS). Sulfur atoms were implanted into high-quality undoped homoepitaxial diamond (100) film grown by microwave plasma assisted chemical vapor deposition onto high-temperature and high-pressure synthetic Ib diamond (100) substrates up to the concentration of 10¹⁷∼10²⁰/cm³. They were annealed at 700∼800°C after the implantation. The 389nm and 5RL centers attributed to the defect, which involves the interstitial carbon atoms, were observed in the CL spectra after the annealing. The displacement of sulfur dopant was less than 0.14A from <001> axis, and less than 0.07A from <011> axis determined by ion channeling-PIXE. The substitutional fraction of sulfur was 0.5 and 0.7 along <001> and along <011> direction, respectively. The depth profile of the distribution of the implanted sulfur obtained by SIMS coincides with that of simulated vacancy depth profile associated with the sulfur implantation. These results suggest that sulfur has a possibility to contribute to the electrical conductivity as an active dopant in diamond. Present results, however, implies that sulfur-residual radiation damage complex prevents from obtaining high substitutional fraction of sulfur.