Studies of the EPR parameters and defect structure for tetrahedral Fe 3+ centers in zinc oxide

The relations between the electron paramagnetic resonance (EPR) parameters and crystal structure of Fe 3+ :ZnO crystals have been established. On the basis of this, the EPR parameters D , (a‐F) and the zero‐field splitting (ZFS) δ 1 , δ 2 of the ground state for Fe 3+ in Fe 3+ :ZnO crystals are theoretically investigated using the complete diagonalization method (CDM). The theoretical second‐order EPR parameter D , the fourth‐order EPR parameter (a‐F), and the ZFS of the ground state: δ 1 , δ 2 for Fe 3+ in Fe 3+ :ZnO yield a good agreement with experimental findings when the three O 2– ions below the Fe 3+ ion rotate by Δ θ in the range 0.475–0.562° away from the [111] axis. Hence, the local structure distortion effect plays an important role in explaining the spectroscopic properties of Fe 3+ ions in Fe 3+ :ZnO crystals. Our approach takes into account the spin–orbit (SO) interaction as well as the spin–spin (SS), spin–other–orbit (SOO), and orbit–orbit (OO) interactions omitted in previous studies. This shows that although the SO interaction is the most important one, the contributions to the EPR parameters from the other three interactions are appreciable and should not be omitted, especially for the EPR parameter D . (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)