| Summary: | 碩士 === 和春技術學院 === 電機工程研究所 === 92 === A simple chemical vapor deposition (CVD) process has been developed in this research to successfully grow up one-dimensional Gallium Nitride (GaN) nanowires on silicon substrates, and as well further with metal catalysis via Vapor-Liquid-Solid (VLS) mechanism to manufacture a large number of GaN nanowires in the length of up to several micrometers with average diameter of about 50 nm in the range of 10~200 nm. The approaching way in this study is to investigate the effects of process parameters on the diameter and length, quantity density, and structure and morphology of as-grown nanowires by means of adding different metal catalyst and holding at different temperatures for several durations in the CVD tube furnace. In experimental analyses, scanning electron microscope (SEM) and X-ray diffraction meter were used to examine the GaN nanowires of specimens in some details and to identify the phases respectively. Experimental results show the critical requirement of overcoming certain energy barrier under temperature restriction in order to grow up the nanowires of gallium nitride, or otherwise it would be impossible to sprout any nanowire if without reaching to such growth temperatures. Besides, it is general for the CVD synthesis to first form some GaN particles on the substrate at lower temperatures, and then from their agglomerates to sprout the nanowires, i.e. it is critical and necessary to provide enough driving force in dynamics (e.g. through amorphous structure) for promoting the nucleation and growth of nanowires. The increase of reaction time at holding temperatures would lead to obviously the increase of diameter and length of GaN wires and also improve the yield of nanowires, albeit often accompanied with some wires further developing in diameter up to micrometer scale. The species and concentration of metal catalyst in addition could also have certain positive effect on the control of homogeneity in the diameters of GaN wires for CVD manufacturing process.
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