| Summary: | 碩士 === 國立中正大學 === 化學工程研究所 === 100 === Gallium oxide is one of the most potential nanomaterials among metal oxides, and its unique properties attract much attention from many researchers. In the process of preparing gallium oxide materials, chemical vapor deposition is the most common method to fabricate gallium oxide nanomaterials. This is because its preparation process is easy and it does not need a high-cost equipment. In order to prepare catalyst for gallium oxide nanowires, the sputtering method is usually used to coat with a layer of gold film on the substrate so that gold nanoparticles are formed via surface tension under high-temperature. Controlling the time lapse of sputtering process can effectively control the size of gold nanoparticles, and the size of gold nanoparticles is corrected with size of the nanowires.
Because the usage of gold catalyst is easy to control the size of the nanowires, the gold catalyst is most frequently used as a catalyst for the synthesis of nanowires. Nevertheless, the disadvantages of using gold catalyst to synthesize nanowires are the high cost of materials and restrict on the usage of sputtering equipment. In order to improve its shortcomings, this study provides a simple method in which an electroless plating process is used to prepare Ni, Co, Ni(P) catalysts. These Ni, Co, Ni(P) catalysts could be substituted for Au catalysts. One could observe the size of nanoparticles and gallium oxide nanostructure by changing the plating time lapse.
In this work, we found that when the electroless plating time lapse is shorter, the gallium oxide nanostructures are nanosheet, when the electroless plating time lapse is longer, the gallium oxide nanostructures are nanowires, due to less catalyst nanoparticles on the substrate. In addition to the usage of various catalysts to successfully prepare gallium oxide materials, we also found that the defects could also stimulate the growth of the gallium oxide nanostructure after etching the silicon substrate. Furthermore, the clear evidence reveal that the short-term growth across various catalysts used to prepare gallium oxide materials showed that the growth mechanism in using Ni and Co catalysts follows the Vapor-Solid (VS) mechanism, while the growth mechanism in using Au, Ni(P) catalyst follows the Vapor-Liquid-Solid (VLS) mechanism.
Except for using various catalysts to successfully prepare gallium oxide nanomaterials in the study, this research also observed the morphology changes, and studied their optical properties by doping Sn, Zn elements in the preparation of gallium oxide nanomaterials. The evidence of this study suggested that the undoped synthesis of gallium oxide generates the blue emission, while the synthesis of gallium oxide doped with Sn, the wavelength of emission generates the red-shift phenomenon. Doping Zn, the wavelength of emission generates the blue-shifted phenomenon. More detailed results are presented in the main text.
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