Tetrahedral ${\mathrm{Mn}}_{i4\mathrm{}}$ cluster in silicon

${\mathrm{Mn}}_{i4\mathrm{}}^0$ clusters were investigated by electron paramagnetic resonance in silicon specimens with initial doping concentrations between $1.5\times {10}^{15}\hspace{0.5em}\mathrm{P}{\mathrm{cm}}^{-3}$ and $5\times {10}^{16}\hspace{0.5em}\mathrm{B}{\mathrm{cm}}^{-3}.$ In n-type samples and in intrinsic samples, we obtained the EPR spectrum of the well-known ${\mathrm{Mn}}_{i4\mathrm{}}^0$ cluster, whereas in p-type material we observed an unknown EPR spectrum of cubic symmetry which we attribute to a ${\mathrm{Mn}}_{i4\mathrm{}}^{+}$ cluster. This spectrum is highly light sensitive. Its $+/0\mathrm{}$ level was found near midgap by photo-EPR. In highly doped p-type material we could prove the presence of a ${\mathrm{Mn}}_{i4\mathrm{}}^{2+}$ center which shows no EPR spectrum, but is transformed into ${\mathrm{Mn}}_{i4\mathrm{}}^{+}$ under illumination.