Abstract:
In ZnO the impurity ion of iron which substitutes the zinc ion must be in the Fe$^{2+}$ state ($d^6$ – configuration), but it often manifests itself as Fe$^{3+}$$(d^5)$. In 1992 the narrow line $A$ appearing as a result of intracentral transition of Fe$^{3+}$$(d^5)$ ion in the photoluminescence (PL) spectrum of ZnO at the energy of 1.7874 eV was seen for the first time. This line was accompanied by the intensive vibrational phone which was caused by the ZnO lattice phonons. In this work significant differences between the PL spectrum of ZnMnO : Fe$^{3+}$ and PL spectrum of ZnO : Fe$^{3+}$ are shown. In PL spectrum of ZnMnO : Fe$^{3+}$ line A is splitted into two components. Under the influence of light in ZnMnO : Fe$^{3+}$ the exciton localized on Mn$^{2+}$–4O$^{2-}$ – cluster appears. The Auger relaxation of this exciton leads to the excitation of $d^5$-configuration of Fe$^{3+}$ ion, not the Mn$^{2+}$ ion. In our case the nonstandard Auger process with two impurity centers with $^6A_1$ ground states takes place.
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