The effect of substrate temperature on the microstructural, electrical and optical properties of Sn-doped indium oxide thin films

In this work, Sn doping In2O3 (ITO) thin films with a thickness of 200 nm were deposited on glass substrates by electron beam evaporation (EBE) method at different substrate temperatures. The crystal structure of these films was studied by X-ray diffraction technique. The sheet resistance was measured by a four-point probe. Van der Pauw method was used to measure carrier density and mobility of ITO films. The optical transmittance spectra were recorded in the wavelength region of 300–800 nm. Scanning electron microscope (SEM) has been used for the surface morphology analysis. The prepared ITO films exhibited body-centered cubic (BCC) structure with preferred orientation of growth along the (2 2 2) crystalline plane. The grain size of the films increases by rising the substrate temperature. Transparency of the films, over the visible light region, is increased with increasing the substrate temperature. It is found that the electrical properties of ITO films are significantly affected by substrate temperature. The electrical resistivity decreases with increasing substrate temperature, whereas the carrier density and mobility are enhanced with an increase in substrate temperature. The evaluated values of energy band gap Eg for ITO films were increase from 3.84 eV to 3.91 eV with increasing the substrate temperatures from 200 °C to 500 °C. The SEM micrographs of the films revealed a homogeneous growth without perceptible cracks with particles which are well covered on the substrate

Surface Characterization and Morphology of Conducting Polypyrrole Thin Films during Polymer Growth on ITO Glass Electrode

Statistical, morphological, and fractal analyses of the conducting polypyrrole (PPy) thin films during polymer growth on the indium tin oxide (ITO) glass electrode were investigated. Cyclic voltammetry (CV) was used to synthesize polymer thin films with different thicknesses and for calculation of fractal dimensions (<i>D</i>_f). Atomic force microscopy (AFM) as a powerful technique was employed to statistically study and analyze the morphology of different types of thin film surfaces with parameters such as root mean square (RMS), kurtosis (<i>Ku</i>), skewness (<i>Sk</i>), and <i>D</i>_f. In calculating the fractal dimensions from AFM images of different thin films, power spectral density, perimeter–area, and box-counting methods were used. The results show that the fractal dimensions increased with increasing thicknesses of the films. RMS, <i>Ku</i>, and <i>Sk</i> parameters of the films were changed with increasing film thicknesses. Moreover, X-ray diffraction (XRD) analysis technique confirmed the process of growing polymers on polycrystalline indium tin oxide (ITO) and increasing the crystallinity of PPy during film growth