Trigonal gold-pair center in silicon

Abstract

The electronic and vibrational properties of a gold-related center in silicon have been studied by Fourier-transform spectroscopy using uniaxial stress and Zeeman spectroscopy. Thirteen different characteristic line series have been identified, of which 11 consist of a relatively intense zero-phonon line followed by several phonon replicas. The line series are assigned to internal transitions at a gold-related center in two different charge states, i.e., the neutral and negatively charged states for which the phonon energy is about 119.8 and 105.7 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$, respectively. A Huang-Rhys factor of 1.4\ifmmode\pm\else\textpm\fi{}0.1 was determined for the \ensuremath{\Elzxh}\ensuremath{\omega}=119.8 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ series. The center has trigonal symmetry deduced from uniaxial stress and Zeeman experiments. A dissociation energy of about 1.7 eV was determined from an isothermal annealing study. The trigonal symmetry and the high dissociation energy strongly suggest that the center consists of two nearest-neighbor substitutional gold atoms. A divacancy model is employed that makes a qualitative understanding of the electronic properties of the center possible.