Optical and Electrical Properties of Nano Crystalline Transparent Conducting SnO_2 Thin Films Grown by Nebulized Spray Pyrolysis Technique at Different Substrate Temperature

摘要

Nano crystalline, transparent conducting tin dioxide (SnO_2) thin films were grown on glass substrates using the nebulized spray pyrolysis technique at various substrate temperatures 250 ℃, 300 ℃ and 350 ℃ respectively. The XRD studies reveal that the structure of SnO_2 thin films is a tetragonal system with a rutile structure. The preferred orientation of SnO_2 changed from (2 0 0) to (1 0 1) as the substrate temperature increased. The morphology and the surface roughness of thin films were studied by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) respectively. The optical absorption and transmittance spectra were recorded using UV-Vis spectroscopy and its band gap values were calculated as 4.05 eV, 3.9 eV and 3.8 eV for direct allowed and 1.60 eV, 1.70 eV and 1.78 eV for indirect allowed transition. Four probe method was adopted to study the room temperature resistivity of SnO_2 films and were determined as 46.11 Ωcm, 16.45 Ωcm and 10.53 Ωcm respectively. Activation energy was also determined from the I-V plot for all three films. N-type conductivity of the tin dioxide thin films was observed by hot probe technique. As the prepared films have high optical transmittance (＞80%) in the visible region and high room temperature conductivity, prepared SnO_2 thin films can be used as the transparent conducting oxide (TCO) material.