TRIGONAL GOLD-PAIR CENTER IN SILICON

The electronic and vibrational properties of a gold-related center in silicon have been studied by Fourier-transform spectroscopy using unia xial 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 lin e series are assigned to internal transitions at a gold-related center in two different charge states, i.e., the neutral and negatively char ged states for which the phonon energy is about 119.8 and 105.7 cm-1, respectively. A Huang-Rhys factor of 1.4+/-0.1 was determined for the HBARomega = 119.8 cm-1 series. The center has trigonal symmetry deduce d from uniaxial stress and Zeeman experiments. A dissociation energy o f about 1.7 eV was determined from an isothermal annealing study. The trigonal symmetry and the high dissociation energy strongly suggest th at the center consists of two nearest-neighbor substitutional gold ato ms. A divacancy model is employed that makes a qualitative understandi ng of the electronic properties of the center possible.