Optical Detection of Magnetic Resonance for a Deep-Level Defect in Silicon

Optical detection of magnetic resonance is reported for the 0.97-eV luminescence in neutron-irradiated silicon. The resonance is of an excited triplet ($S=1$) state of the defect, which is not the radiative state, known to be a singlet ($S=0$). The spectrum is unusual in that it is characteristic of a statically distorted defect (from C₃ᵥ to C₁ₕ), but with residual dynamic tunneling effects where random strain stabilizes mixtures of the static C₁ₕ distortions. Vacancy-related models previously suggested for the defect are tentatively ruled out.