Investigation of the structural, and magnetic properties of Zn, Ni and Co doped iron oxide thin films

In this thesis, iron oxide compound and double, triple and quaternary iron oxide compounds with Zn, Ni, Co metal dopants were grown by using Chemical Spray Pyrolysis (SP) technique. The structural, optical, electrical and magnetic properties of Fe2O3, ZnxFe3-xO4, NixZn1-xFe2O4 ve CoxZn1-xFe2O4 compounds have been extensively investigated. XRD, XPS, Raman, SEM-EDAX and AFM techniques have been used for structural analysis; Absorption technique has been used for optical properties; Hall and Vibrating sample magnetometer (VSM) techniques have been used for electrical and magnetic properties. Many parameters such as substrate, substrate temperature, the salts, spraying distance, solvent type, molarity and deposition time have carefully been choosen to obtain the best growth condition in this tecnique. XRD analysis of the growth films revealed that Fe2O3 film has tetragonal, ZnxFe3-xO4 film has heavily cubic, NixZn1-xFe2O4 and CoxZn1-xFe2O4 films have cubic polycrystalline structures. The XPS results show that Fe3+ (Fe2O3) ion has 711,65 eV binding energy for 2p3\2 orbital; Zn 2+(ZnxFe3-xO4) ion has 1024,23 eV binding energy for 2p3\2 orbital, Co 2+(CoxZn1-xFe2O4) ions has 782,66 eV binding energy for 2p3\2 orbital, Ni 2+(NixZn1-xFe 2O4) ion has 856,00 eV binding energy for 2p 3\2 orbital. Raman analysis result showed that, characteristic Raman exchange peaks belonging to Fe2O3 (217 cm-1, 275 cm-1), ZnxFe3-xO4 (382 cm-1, 483 cm-1), NixZn1-xFe2O4 (462 cm-1, 677 cm-1) and CoxZn1-xFe2O4 (459 cm-1,612 cm-1) compounds were in the strenching mode. SEM-EDAX analysis showed that, the crystal structure and grain boundaries of the structure have been seen and the crystal structure has been formed. Additionally, the elements being in the compound structure were completely determined by EDAX technique. In the AFM results, there are peaks and troughs in some places, partially homogenous and also have a linear roughness between 28 nm and 115 nm. In terms of optical properties, the band gap values obtained for the absorption measurements of Fe2O3, ZnxFe3-xO4, NixZn1-xFe2O4 ve CoxZn1-xFe2O4 films are 2,16 eV, 2,14 eV, 2,00 eV, 2.10 eV respectively. According to Hall measurements used to characterise electrical and magnetic properties, the p-type carrier density values of Fe2O3, ZnxFe3-xO4, NixZn1-xFe2O4 and CoxZn1-xFe2O4 films were 4.25*1016 cm-3, 7,28*1018 cm-3, 1,064*1016 cm-3, 3,80*1015 cm-3 respectively. Finally, the resulting from the VSM measurement according to the intensity hysteresis curves, we can write NixZn1-xFe2O4, CoxZn1-xFe2O4, Fe2O3, ZnxFe3-xO4 from minumum one to maximum ones. When we consider the magnetization state, the hardest magnetization property is seen in ZnxFe3-xO4 film and Fe2O3 film have showed the softest magnetization property. When evaluating films grown by SP technique in terms of device applications; CoxZn1-xFe2O4 film is suitable for gaz sensor, NixZn1-xFe2O4 film is suitable for magnetic rectifier contact, Fe2O3 and ZnxFe3-xO4 films are suitable for spintronic applications.