Papers by Author: Yung Kuan Tseng

Abstract: This Study applies to Stöber method for synthesis an characterization of even-sized SiO₂ micrometer sphere; and then applies to sol-gel method for encapsulation for one layer of ZnO at SiO₂ spherical surface after regarded it as core so that synthesis SiO₂/ZnO core-shell spheres successfully. And observe morphology by FE-SEM and crossection by TEM. The TEM specimen were cut by two-beam FIB. Besides, EDS, XRD and UV-Visible spectroscopy were using for the analysis of composition, crystallization structure, and absorption spectrum, respectively. Experimental results showed that, SiO₂ spherical surface became smooth after deposition for zinc oxide. The specimen made by FIB more obviously was observed for core-shell distribution by TEM. EDS analysis made us clearly see shell signal with ZnO content, but core signal only is SiO₂ content. XRD analysis indicated its core-shell sphere signal possessing ZnO content, but UV-Visible absorption spectrometer displayed ZnO has been absorbed in range of UV light, in contrast, it is not absorbed in range of visible light.

Abstract: This study proposes a novel sol-gel method of fabricating the two-dimensional flakes polycrystalline zinc oxide (ZnO). Apply zinc acetate dehydrate in glycerol and hydrolyzed to get the precursor zinc alkoxide particles at 160°C, and self-assemble into flakes ZnO nanostructures, and then got higer crystallinity polycrystalline ZnO after calcination for one hour at 500°C. Field-emission scanning electron microscopy (FE-SEM) was used to observe the morphology of the flakes. Its size got to a few μm². Analyze the crystal structure and crystallinity by X-ray powder diffraction (XRD). After calcination for one hour at 500°C, we can determine it is the hexagonal wurtzite structure of ZnO. And TGA/DSC to observe the loss and phase change of the solution. The Study has successfully synthesized ZnO polycrystalline flakes by sol-gel method.

Abstract: This study is mainly to control the density of zinc oxide nanowires arrays as main axis. We spin coated AZO thin film to Si/SiO₂ substrate by hydrothermal method growing ZnO nanowire arrays on a substrate by spin coating a layer of zinc powder mixed with SiO₂ film, and controlled the concentration of zinc. We can easily obtain a nanowire array density control. In this experiment, we investigated different centrifugation speed, time, zinc concentration, temperature and other variable parameters. Through field emission scanning electron microscopy observation of dispersive zinc oxide nanowires and dispersion situation, it was found that using different doping concentration and rotation speed, different densities can be successfully obtained for ZnO nanowires array. Dispersion of zinc oxide nanowires by hydrothermal method with increasing time, the diameter and length will increase significantly.

Abstract: The purpose of this study was to discuss the effects of different solvent systems for aluminum doped zinc oxide (AZO) thin film deposition by using the sol-gel method. In the conventional sol-gel method of producing AZO thin films, the solution selected as the precursor solvent was used ethylene glycol monomethylether (EGME), which in this study propylene glycol mono-methyl ether (PGME) was used. The precursor solution was observed by TGA/DSC to understand the variations while heating. The two prepared precursor solutions were then respectively spin coated onto substrates of boron silicate glass. XRD analysis indicated both showed significant c-axis preferred orientation. The surface morphology of the films was observed by FESEM, which showed that the thin film surface by PGME solvent was smoother and dense. A four-point probe was used to measure the electrical resistance of the thin films, which the measured results indicated that the thin film produced by PGME had lower resistivity than those produced by EGME. Resulting with a thin film electric resistance reaching as low as 3.474×10^-3(W×cm). The visible light transparency was determined via UV-vis analysis. Results showed that the average transparency of thin films produced by the EGME solvent reached 95% and above, where the average transparency from PGME solvent still reached 90% and above. Experimental results demonstrated that PGME is a good option to synthesize AZO thin films.