The annealing behavior of defects observed in electron paramagnetic resonance (EPR) and photoluminescence (PL) is discussed. We consider the divacancy (the P6/P7 EPR centers) and a previously unreported EPR center that we suggest is a $V_{\mathrm{C}}\text{−}{V}_{\mathrm{Si}}\text{−}{V}_{\mathrm{C}}$ trivacancy and their relationship with each other and with the UD1–3 series of PL lines near $1\mathrm{eV}$. We observe that the divacancy and the UD2 PL lines annealing behavior is strongly correlated further establishing the relationship between the EPR and PL centers. We present a detailed discussion of this center and its ${}^{29}\mathrm{Si}$ and ${}^{13}\mathrm{C}$ hyperfine spectra which supports our assignment as a trivacancy. The intensity of this center increases with annealing temperature as the divacancy decreases and there is a sample-to-sample correspondence between the overall intensities of the two centers. However, the details of their annealing suggest a more complex relationship than a simple one-to-one transformation. In addition, while the UD1 PL increases with annealing temperature, sample-to-sample variations indicate it is not related to this EPR center.

• Received 14 July 2006

DOI:https://doi.org/10.1103/PhysRevB.74.235201