Abstract
Electron-spin-resonance studies of a series of air-annealed samples of glassy Si having various degrees of enrichment (or depletion) in the isotope have confirmed that a -ray-induced doublet of 420-G splitting is the hyperfine structure of the well-known center. This finding validates the widely accepted model of the center as an unpaired electron spin in a dangling hybrid orbital of a silicon bonded to three oxygens in the glass structure and eliminates a recently proposed alternative model. Continuous-wave microwave saturation measurements at ∼9.2 GHz were carried out in order to establish spin-lattice relaxation behavior and to determine absolute line intensities in the low-power limit. The spin-lattice relaxation process for the center is shown to be dominated by a hyperfine mechanism. Spin-lattice relaxation times could be extracted from the cw saturation data only by means of a semiempirical formulation differing from the usual approaches found in the literature.
- Received 9 April 1979
DOI:https://doi.org/10.1103/PhysRevB.20.1823
©1979 American Physical Society