Structural, optical and magnetic properties of Mn-doped ZnO thin films prepared by sol-gel method

Undoped and Mn-doped ZnO thin films were prepared on quartz glass and Si(1 0 0) substrates by the sol-gel method at room temperature, and the effects of Mn content on the structural, optical, and magnetic properties of these films were investigated. X-ray diffraction patterns reveal that all the films are single phase and have wurtzite structure with (0 0 2) preferential orientation along c-axis, indicating there are not any secondary phases. X-ray photoelectron spectroscopy patterns suggest that Mn2+ ions were successfully incorporated into the lattice position of Zn2+ ions in ZnO host. Optical transmittances of the films were recorded in the wavelength range of 300-800 nm, and the band gaps of the films were determined. As the content of Mn increases, the crystallite size and the optical band gap of the films decrease while the crystalline quality deteriorates gradually. The intensity of photoluminescence spectra is suppressed with Mn doping. Magnetic measurements indicated that undoped ZnO was diamagnetic in nature whereas Mn-doped ZnO samples exhibited ferromagnetic behavior at room temperature, which is possibly related to the substitution of Mn2+ ions for Zn2+ ions in the ZnO lattice. It is also found that the Mn doping content can affect the ferromagnetic behavior of the films effectively. (C) 2013 Elsevier B.V. All rights reserved.