Single, co-doping and triple doping Fe element in the ZnO crystal matrices

Fe element settlement in the ZnO matrices has been investigated through prepared single doped, co-doped with Mg and triple doped with Mg and Cu by a systematic x-ray Photoelectron Spectroscopy (XPS) and Electron Paramagnetic Resonance (EPR) measurements as well as the structural and morphological analysis through x-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) measurements. Also, effects of different solutions, nitrate and chlorate, on the Fe doping has been studied. XRD measurements have exhibited that crystal quality of the thin films deteriorates as the Fe doping level increases. On the other hand, Fe co-doped and triple doped with Mg and Mg + Cu has converted the dominant crystal plane direction from (002) to (101) and (100), respectively. Single Fe doped ZnO thin films has shown the smoothest and uniform thin film surfaces while co-doped and the triple doped thin films has displayed overgrown surface morphology with 3D morphology. The XPS has been used to investigate the chemical environment of the Fe in the ZnO lattice and Fe element has been found to be in the Fe³⁺ state. Two signals have been observed at g ∼ 2.0 and g ∼ 4.3 which are attributed an electron trapped into oxygen vacancy and isolated Fe³⁺. As the concentration of Fe doping increases, the intensity of g ∼ 2.0 signal intensity increases significantly, while the g ∼ 4.3 signal intensity increases slowly. Temperature dependence of EPR signals in terms of intensity, linewidth and g-factor been investigated. (paper)