Hydrogen at zinc vacancy of ZnO: an EPR and ESEEM study.

An electron paramagnetic resonance (EPR) spectrum, labeled S1, with small-splitting doublet accompanied by weak satellites is observed in ZnO irradiated with 2 MeV electrons. The obtained structure is shown to be the hyperfine structure due to the dipolar interaction between an unpaired electron spin and a nuclear spin of hydrogen (H). The observation of the nuclear Zeeman frequency of H in electron spin echo envelope modulation experiments further confirmed the presence of a hydrogen atom in S1. From the observed spin-Hamiltonian parameters, S1 is identified to be the partly H-passivated Zn vacancy, V_Zn H₊, with the H₊ ion making a short O-H bond with only one nearest O neighbor of VZn in the basal plane, being off the substitutional site, while the unpaired electron spin, which gives rise to the observed EPR signal, is localized on the p orbital of another O neighbor also in the basal plane. [ABSTRACT FROM AUTHOR]