THIN FILM SYNTHESIS IN COMPOUND OXIDES AND THEIR ELECTRICAL AND MAGNETIC CHARACTERIZATION

Abstract

In this project TM (Transition Metal) doped ZnO thin films Zn(1-X)FeXO (0 < X < 20) with molarity 1M were synthesized by sol-gel method and deposited the on glass substrate by spincoating. Films were synthesized by preheating at 200 ºC for 10 minutes after each coating and annealing at 500 ˚C temperature for 2 hours followed by furnace cooling. Structural, Magnetic and electrical properties of the thin film samples were analyzed by X-ray diffraction (XRD), FESEM, SPM (Scanning Probe Microscopy), HRTEM, SQUID (Superconducting Quantum Interference Device), two probe and four probe set up. XRD analysis show that all samples have a wurtzite hexagonal structure and films have preferred orientation along the (101) plane and no secondary phases were present for Fe doping concentration of (0-15 at.%) however for 20 at.% very small amount of secondary phases were detected. As Fe content increases peak intensity decreases and shift towards higher angle (2θ value) side due to c-axis (lattice constant) decreases implying Fe³+ (0.68 Å) is successfully substituted at Zn2+ (0.74 Å) sites in ZnO lattice. FE- SEM micrographs were used to study the structural, elemental and morphological properties of the thin films and results show that samples are uniform and have a homogeneous surface distribution of grains. By increasing the Fe concentration in ZnO the particle size of the thin films were decreased. Magnetic properties of the samples have been studied by SQUID, M-H curves (300K) and M-T curves (5K – 330K), the analysis revealed that samples have M – H curves with a small saturation magnetization (Ms) and remanence magnetization (Mr), which indicates the Room Temperature Ferromagnetic (RTFM) properties. M-T curves show for Fe (0-20 at.%) all samples have positive Ms (saturation magnetization) i.e. ferromagnetic properties and for Fe (20 at.%) small amount of secondary phases were detected. Topographical analysis and roughness were determined by SPM. The results show film growth is along c-axis i.e. perpendicular to the substrate and as the Fe doping increases the roughness of the films decreases. Two probe method is used for V-I characteristics and Four probe set used to determine the Resistivity () and Activation energy (EA) of the thin films.