| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 92 === This research deals with the growth of gallium nitride quantum dots by molecular beam Epitaxy (MBE), and gallium oxide nanowires by chemical vapor deposition (CVD). For the former, we studied various surface morphologies of the GaN epitaxial nanostuctures by changing two nitridation times for the buffer layer. The results proved that the quantum dot growth was followed by S-K growth mode. Moreover, the size, density, and roughness of the island structures increased when the growth time increased. However, the defects were introduced to reduce the stress accumulation during the continues growth of epitaxy. The photoluminescence properties showed the wavelength were shifted from 399 nm to 387 nm when 2D surface transformed to 3D island structure.
For the growth of the Ga2O3 nanowires in CVD reaction, we observed the unstable nucleus of initial products would gain more mobility and transformed into stable cores when we raised the growth temperture. Different growth temperatures would promote the anisotropic growth of the Ga2O3 crystals to variant 1-D structures. It could let the surface morphology change to film structure and the crystallinity became worse when the NH3 flow rate increased. The reason is the proportion of the NH3 content increased along with the flow rate, because the bonding type of the products gradually changed from Ga-N to Ga-O bonding. Finally we studied the photoluminescence properties of various 1-D nanostructures. We discovered lights of various wavelengths emitted from 1-D nanostructures with powders, and the reasons are ascribed to the defects of the 1-D nanostuctures.
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