Optically detected magnetic resonance shows that a broad, green emission band in ZnO at 2.45 eV originates from a spintriplet-recombination characterised by g || c =1.984 and g ⊥ c =2.025 (parallel and perpendicular to the crystallographic c -axis, respectively) and a zero-field splitting of D =260×10 −4 cm −1 . These parameters and the polarisation properties of the emission are very similar to the anion vacancies in CaO but not compatible with the Zeeman results on ZnO : Cu.
