Structures And Magnetic Properties Of Transition Metal Doped ZnO-based Diluted Magnetic Semiconductors

Diluted magnetic semiconductors(DMSs)plays an irreplaceable role in spintronics devices because it has the advantages of semiconductors and magnetic materials.ZnO-based diluted magnetic semiconductors(DMSs)have been extensively investigated since ZnO has distinctive physical and chemical properties.In this work,TM-doped ZnO samples were synthesized by co-precipitation method.The structures and magnetic properties of Zn1-xTM_xO powder had been investigated in detail by infrared spectroscopy(IR),the X-ray diffraction spectra,scanning electron microscope figure,X-ray photoelectron spectroscopy(XPS)and magnetic properties.This thesis includes six chapters:Firstly,the research progress of DMSs and ZnO-based DMSs were summarized.We also introduced the magnetic properties of ZnO-based DMSs.Part two introduce the preparation and characterization methods of TM-doped ZnO-based DMSs.From the third part to the sixth part,the microstructure and properties of as prepared Mn,Fe,Co and Cu-doped ZnO samples had been analyzed.The structural analysis showed that homogeneous Mn,Fe,Co and Cu-doped ZnO samples had been successfully synthesized and the solubility of Co was largest in the ZnO,up to 10%.The optical properties of TM-doped ZnO-based DMSs had been studied by UV-Vis absorption spectra and the results showed that as prepared samples had a maximum absorption peak in the ultraviolet area around 360~365nm that was intrinsic absorption of ZnO.Furthermore,the absorption of TM-doped ZnO increased in the visible region with increasing doping concentration.Meanwhile,the band gap of ZnO decreased and the absorption edge had a red shift which indicated that TM ions were in ZnO lattice successfully and affected the optical properties of ZnO.The magnetic properties of TM-doped ZnO-based DMSs had been investigated by MPMS and the analysis confirmed that all the samples exhibited ferromagnetic behavior at room temperature(RT).Among the rest,with the increase of Cu and Co doping concentration,the magnetic properties first increased and then decreased.As the doping concentration of Fe and Mn increased,the magnetic properties increased.