Influence of Annealing Temperature on Structural, Morphological, Optical and Electrical Properties of Sol-Gel SnO2 Thin Films

SnO2 thin films were prepared on glass substrates by sol-gel spin coating method using stannous chloride dihydrate and ethyl alcohol absolute as raw materials at annealing temperature 450-550 degrees C. The crystal phase was measured by X-ray diffraction (XRD) and showed tetragonal rutile structure with a preferential orientation of (110). Atomic force microscope (AFM) and Scanning Electron Microscope (SEM) images revealed the homogeneous grains distribution, and SEM images showed the obvious rectangular objects corresponding to tetragonal structure. Optical properties were observed by the transmittance in ultraviolet-visible (UV-Vis) region and optical energy gap, which revealed the transmittance over 75% and energy gap between 3.84 eV and 3.89 eV. Finally, I-V characteristics were tested to research electrical properties, and found the gradual non-linear property and the increase of resistance.