Studies of the EPR parameters and defect structure for tetrahedral Fe3+ centers in zinc oxide

Abstract

AbstractThe relations between the electron paramagnetic resonance (EPR) parameters and crystal structure of Fe3+:ZnO crystals have been established. On the basis of this, the EPR parameters D, (a‐F) and the zero‐field splitting (ZFS) δ1, δ2 of the ground state for Fe3+ in Fe3+: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: δ1, δ2 for Fe3+ in Fe3+:ZnO yield a good agreement with experimental findings when the three O2– ions below the Fe3+ ion rotate by Δθ 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 Fe3+ ions in Fe3+: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)