EPR investigation of manganese clusters in silicon

Manganese centers were investigated in silicon specimens with initial doping concentrations between $1.5\times {10}^{15}{\mathrm{P}\mathrm{}\mathrm{cm}}^{-3}$ and $6\times {10}^{15}{\mathrm{B}\mathrm{}\mathrm{cm}}^{-3}.$ All known Mn centers could be observed but the cluster ${\mathrm{Mn}}_{i3\mathrm{}}{\mathrm{Mn}}_i$ was missing in highly-boron-doped material, indicating that this center is negatively charged. A new center of trigonal symmetry was observed for an initial doping of $6\times {10}^{15}{\mathrm{B}\mathrm{}\mathrm{cm}}^{-3}$ and identified as a ${\mathrm{Mn}}_{i3\mathrm{}}^{2+}$ cluster. The EPR signal of this center is strongly light sensitive in contrast to the other known Mn clusters.