EPR and ENDOR observation of orthorhombic Au-Li and Pt-Li pairs in silicon: On the problem of the observation of isolated Au_Si⁰with magnetic resonance

Abstract

We report the obsewation of orthorhombic Au-Li and Pi-Li pairs in Si using EPR and ENDOR techniques and also MCDA spectroscopy. The EPR spectra alone could be mistaken as being due to orthorhombic isolated point defects and ENDOR is required to detect the Li partner of the pair. Comparison of the MCDA spectra with conventional infrared absorption shows that the optical spectra generally associated with the isolated substitutional Au point defect are excited from a paramagnetic ground state. We show that the interpretation of the Si-NL50 centre as the isolated substitutional Au; point defect is unlikely in view of our results.

Magnetic moments of substitutional gold in silicon

“…This model has been supported in the meantime by an experimental investigation by Watkins et al [6] who investigated the Zeeman effect of optical transitions at the Au 0 centre, and characterized its ground state as paramagnetic with S = 1 2 , g = 2.8, and g ⊥ ≈ 0. With these parameters, Greulich-Weber et al [2] were able to interpret their measurements of the magnetic circular dichroism of the absorption. Furthermore, Watkins et al observed rapid reorientation of the tetragonal distortion between the equivalent 100 directions, from which they concluded that the defect is associated with a single gold atom, and not with a gold-correlated complex.…”