Thickness effects on physical and electrical properties of Zn_(0.97)Co_(0.02)In_(0.01)O thin films grown by magnetron sputtering RF

摘要

The effects of thickness on physical properties (structural, morphological, optical and electrical) of Zn0.97Co0.02In0.01O (CIZO) thin films with different thicknesses grown at room temperature were investigated in this study. Zn0.97Co0.02In0.01O thin films have been grown by Radio Frequency magnetron sputtering on glass substrate followed by a rapid annealing treatment at 400 degrees C for 10 min. X-ray diffraction (XRD) measurement display that the Zn0.97Co0.02In0.01O thin films exhibited hexagonal wurtzite phase with a preferred orientation along the c-axis. We observe a strong single peak corresponding to the (002) phase obvious on the diffractograms. The crystallite size values exhibit an increasing tendency and the dislocation density indicates a decreasing trend with increasing thickness, this shows that the material is relaxing. Concerning the SEM micrographs, it was observed that the average grain size increased from 20 nm to 80 nm, with thickness ranging from 150 nm to 450 nm. The roughness surface (RMS) measured by AFM increased from 4.309 nm to 11.392 nm with a rising thickness. Raman spectroscopy was used to study structural properties of complex oxides at a local level. All films were highly transparent in the visible region with an average transmittance of 96%. Growing the thickness enhance the optical band gap, from 3.106 eV to 3.439 eV. Optical parameters such as absorption coefficient, refractive index, dispersion parameters and dielectric constants were studied to investigate the influence of thickness on optical properties of Zn0.97Co0.02In0.01O thin films. The thickness improves the electrical resistivity of Zn0.97Co0.02In0.01O thin films. It has been found from electrical measurements that films with a thickness of 450 nm have the lowest resistivity of 2.9 10(-3) Omega cm. Once the merit factor determined, we noted that the 450 nm sample having a better TCO of value 12.2 10(3) Omega(-1).