Structural, optical, and magnetic properties of Mn-doped ZnO thin film

The Zn1−xMnxO (x=0, 0.16, and 0.25) thin films were grown on fused quartz substrates by reactive magnetron cosputtering. X-ray-diffraction measurement revealed that all the films were single phase and had wurtzite structure with c-axis orientation. As Mn concentration increased in the Zn1−xMnxO films, the c-axis lattice constant and band-gap energy increased gradually. In Raman-scattering studies, an additional Mn-related vibration mode appeared at 520cm−1. E2H phonon line of Zn1−xMnxO alloy was broadened asymmetrically and redshifted as a result of microscopic structural disorder induced by Mn2+ random substitution. The Zn0.84Mn0.16O film exhibited a ferromagnetic characteristic with a Curie temperature of ∼62K. However, with increasing Mn concentration to 25at.%, ferromagnetism disappeared due to the enhanced antiferromagnetic superexchange interactions between neighboring Mn2+ ions.