Optically detected magnetic resonance and photoluminescence studies were made of the S-related metastable defect. It was established that its 2 configurations, A and B, had triclinic (C1) symmetry, and the incorporation of a single impurity atom with nuclear spin of 3/2 was confirmed directly by resolving its hyperfine structure in each optically detected magnetic resonance spectrum. A detailed study of the conversion kinetics indicated that the dominant A → B mechanism under below-bandgap excitation was the result of direct optical excitation; not the result of exciton capture or the energy release which accompanied luminescence. The barrier to the thermally activated B → A return process was 0.10eV; with no sign of an intermediate configuration. Stress-induced splitting of the photoluminescence was satisfactorily analyzed as being the sum of that for a highly localized hole, plus that for a shallow Coulombically-bound effective-mass electron. A tentative model was proposed which involved a substitutional S atom which was paired with an interstitial Cu atom in 2 different nearby configurations. The low symmetry resulted from the tendency of the Cu interstitial to go off-center from the tetrahedral interstitial position.

Sulfur-related metastable luminescence center in silicon P.W.Mason, H.J.Sun, B.Ittermann, S.S.Ostapenko, G.D.Watkins, L.Jeyanathan, M.Singh, G.Davies, E.C.Lightowlers: Physical Review B, 1998, 58[11], 7007-19