Paramagnetic resonance of a new-oxygen-donor related center in silicon

In Czochralski-grown silicon annealed in the temperature range between 650 and 800 ^∘{}C, an anisotropic electron-spin resonance (ESR) spectrum was observed. Analysis of the angular dependence reveals monoclinic (Cₛ) symmetry of the representative g tensor, with one of the principal axes approximately oriented along a [113]-type direction. Investigations of the ESR signals in differently heat-treated crystals show that the center is only formed after a preannealing procedure at T~600 ^∘{}C followed by subsequent annealing. The center seems to be related to a microscopically crystalline oxygen precipitation phase.