Tetrahedral Mn{sub i4} cluster in silicon

Mn{sub i4}{sup 0} clusters were investigated by electron paramagnetic resonance in silicon specimens with initial doping concentrations between 1.5{times}10{sup 15} Pcm{sup {minus}3} and 5{times}10{sup 16} Bcm{sup {minus}3}. In n-type samples and in intrinsic samples, we obtained the EPR spectrum of the well-known Mn{sub i4}{sup 0} cluster, whereas in p-type material we observed an unknown EPR spectrum of cubic symmetry which we attribute to a Mn{sub i4}{sup +} cluster. This spectrum is highly light sensitive. Its +/0 level was found near midgap by photo-EPR. In highly doped p-type material we could prove the presence of a Mn{sub i4}{sup 2+} center which shows no EPR spectrum, but is transformed into Mn{sub i4}{sup +} under illumination.