Structure and photoluminescence properties of Fe-doped ZnO thin films

Zn_1-xFe_xO films were prepared by the radio-frequency (rf) magnetron sputtering technique on n-Si substrates with a composite target of a ceramic polycrystalline ZnO containing several Fe pieces on the surface. X-ray photoelectron spectroscopy study of the Zn_1-xFe_xO films shows that Fe in the as-deposited film exists mainly in the form of Fe²⁺. And x-ray diffraction spectra show that all the films exhibited c-axis orientation. The room temperature photoluminescence (PL) properties of the Zn_1-xFe_xO films were also discussed. Two obvious PL peaks appear at 378 nm and 414 nm, respectively. It is interesting that there is a tendency of redshift for the peak at 378 nm and that the PL intensity increases slightly for the peak at 414 nm as the Fe concentration increases. Discussions have been given to explain the different phenomena.