AN EXPLANATION FOR THE MISSING EPR FROM THE ISOLATED SUBSTITUTIONAL GOLD IMPURITY IN SILICON

EPR from the isolated substitutional Au0 impurity in silicon has never been observed, although EPR is seen for the isolated substitutional Pt- impurity in silicon, which is isoelectronic. The EPR of the Pt- defect shows C2v symmetry, a result of static Jahn-Teller distortions. Using a recently proposed vacancy-model-based electronic structure for Pt-, we show that if the Pt impurity were tunnelling between the two trigonal distortions associated with a given tetragonal distortion, then g perpendicular-to would be nearly zero. We propose that the Au atom is tunnelling and that the tunnelling splitting is at least a few cm-1. With such a tunnelling splitting and with g perpendicular-to nearly zero, under 'typical conditions', the EPR from the Au0 defect would not be observed. We examine the effects of uniaxial stress. Finally, we show how it may be possible to observe EPR from this Au0 defect in silicon.