Defects in irradiated 3C-type material were studied by means of optically detected magnetic resonance techniques. In addition to the isotropic L2 center which had previously been reported, an optically detected magnetic resonance spectrum (L3), with trigonal symmetry and an effective electron spin of S = 1, was observed after annealing at about 750C. The g-values of this center along, and perpendicular, to the trigonal axis were determined to be g|| = 2.0041 and g = 2.0040. The anisotropy of the spectrum was accounted for by spin-spin interactions, with a crystal-field splitting value of 0.042/cm. On the basis of a spectral dependence study of the optically detected magnetic resonance signal, the defect was found to be related to a photoluminescence band in the near-midgap region. The defect was thought to be a complex which involved a Si vacancy and another intrinsic defect; as suggested by its trigonal symmetry and annealing behavior.

N.T.Son, E.Sörman, W.M.Chen, C.Hallin, O.Kordina, B.Monemar, E.Janzén, J.L.Lindström: Physical Review B, 1997, 55[5], 2863-6