Clusters of the form, Mni40, were investigated, by means of electron paramagnetic resonance, in specimens having initial dopant concentrations of 1.5 x 1015P/cm3 or 5 x 1016B/cm3. The electron paramagnetic resonance spectrum of the well-known Mni40 cluster was obtained from n-type or intrinsic samples. In the case of p-type material, an unknown electron paramagnetic resonance spectrum having cubic symmetry was observed and was attributed to a Mni4+ cluster. This spectrum was highly light-sensitive. Its +/0 level was found, using photo-electron paramagnetic resonance, to be near to the mid-gap. In highly-doped p-type material, the presence of a Mni42+ center which exhibited no electron paramagnetic resonance spectrum was proved. This transformed into Mni4+ under illumination.

Tetrahedral Mni4 Cluster in Silicon. J.Wedekind, H.Vollmer, R.Labusch: Physical Review B, 2001, 63[23], 233202 (4pp)