Structure of gold in silicon

Detailed information on the electronic structure of the neutral substitutional gold center in silicon (${\mathrm{Au}}^0$) has been revealed from Zeeman studies of the donor and acceptor excitation spectra at 793 and 611 meV, respectively. The center is paramagnetic, S=1/2, with ${\mathit{g}}_{\mathrm{\parallel }}$≊2.8 and ${\mathit{g}}_{\mathrm{\perp }}$≊0, and has a static 〈100〉 tetragonal distortion. Reorientation between different equivalent distortions is observed even at 1.9 K which establishes the single substitutional nature for this gold center. The fact that ${\mathit{g}}_{\mathrm{\perp }}$≊0 explains the failure to detect ${\mathrm{Au}}^0$ by EPR.