Defects in irradiated silicon: EPR of the tin-vacancy pair

An EPR spectrum, labeled Si-G29, is identified as a lattice vacancy trapped by substitutional tin. The resulting tin-vacancy pair is observed in its neutral ground state with $S=1$. Studies versus wavelength of illumination indicate that it has a donor level at ~Eᵥ+0.35 eV. Analysis of the EPR spectrum leads to a model in which the tin atom resides in a position halfway between two normal silicon atom sites (D3d). It is stable to {~}500 K.