Reduction of the linewidths of deep luminescence centers in 28Si reveals fingerprints of the isotope constituents

Dramatic reductions of the linewidths of well-known deep centers in Si-28 reveal isotopic fingerprints of the constituents. The similar to 1014 meV Cu center, thought to be either a Cu pair or an isolated Cu, is shown to contain four Cu atoms, and the similar to 780 meV Ag center is shown to contain four Ag. The similar to 944 meV Cu-* center, thought to be a different configuration of a Cu pair, in fact contains three Cu and one Ag, and a new two-Cu two-Ag center is found. The similar to 735 meV center, previously assigned to Fe, actually contains Au and three Cu. This suggests a family of four-atom (Cu, Ag, Au) centers.