Preparation Of Tin Dioxide And Its Doped (La, Ru, Mn) Nanobelts And Study On Optical And Gas Sensitive Properties

SnO₂ is an important n-type metal oxide semiconductor material, which was widely used in the gas sensing field. The thesis mainly focuses on the synthesis of La,Ru and Mn doped SnO₂ nanobelts and the optical properties. After that, the devices based on the single La, Ru, and Mn doped SnO₂ nanobelts have been developed respectively and then their sensitive properties were systemically studied.Pure SnO₂ nanobelts and metal earth（La, Ru and Mn） doped SnO₂ nanobelts were prepared by thermal evaporation successfully. The samples were characterized by scanning electron microscope（SEM）, high-resolution transmission electron microscope（HRTEM）, X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, X-ray energy spectrum（EDS）. Their optical properties were also examined by UV-visible（UV-vis）, Photoluminiscence（PL） and Raman respectively. In addition,the sensing mechanism of the device was analysized and discussed. The important results are as follows:On the gas-sensing properties, the optimum operating temperatures of La, Ru and Mn doped SnO₂ nanobelts devices were 210℃, which are lower than those of the pure SnO₂ nanobelt. La doped SnO₂ nanobelt is sensitive to ethanediol gas with a response of 9.60 at 100 ppm of ethanediol gases; Ru doped SnO₂ nanobelt is more sensitive to acetone gas with a response of 6.15 at 100 ppm of acetone gases; Mn doped SnO₂ nanobelt is more sensitive to ethanol gas with a response of 2.64 at 100 ppm of ethanol gases.On the optical properties, the UV-Vis results revealed that the bandgap of La, Ru and Mn doped SnO₂ nanobelts are 3.25 eV, 3.37 eV, and 3.43 eV respectively at room temperature, which are lower than that of the pure SnO₂ nanobelts（³.66 eV）; the strongest peak and the second strong peak of PL of Ru doped SnO₂ nanobelts have shifted towards low frequency（denoted as red shift） by 3 and 1 nm respectively;whereas the strongest peaks of La and Mn doped SnO₂ nanobelts have shifted to high frequency（denoted as blue shift） by 3 and 6 nm respectively, the second peak of La and Mn doped SnO₂ nanobelts has occured a red shift by 2 and 5 nm respectively;Raman spectrum peak of La, Ru and Mn doped SnO₂ nanobelts also proved a little red shift as compare to that of pure SnO₂ nanobelts. The possible reason of this phenomena may be related to the changes of grain size or crystal defects.