| Summary: | 碩士 === 國立臺灣科技大學 === 材料科技研究所 === 91 === Zinc oxide (ZnO) is a versatile Ⅱ-Ⅵ ceramic material also nonstoichiometric semiconductor with various applications, such as varistors, piezoelectric elements, surface acoustic wave devices, gas sensors, luminescent materials, thin-film solar cells ,and so on.
In this thesis, ZnO powders were synthesized by sol-gel method with two different process. The relationship between morphology, microstructure, crystallinity and luminescence properties was investigated in order to control monodispersed colloidal particles.We believe these powders could be used as light-emitting and waveguiding devies in optoelectronic applications.
In first procedure, ZnO powders were prepared in room temperature by using zinc acetate dihydrate, methanol and sodium hydroxide. The particles were uniform sizes of 20nm crystallite when added 4ml NaOH. The sodium ion-induecd amorphous nanowires with diameter 20~50nm, length 3μm, were fonud on the surface of 50nm ZnO crystalline powders when added 8ml NaOH. Photoluminescence spectrums show the defect emissions were stronger than UV emissions in crystallite powders as well as nanowires.
In another procedure, ZnO colloidal spheres were formed by hydrolysis of zinc acetate dihydrate in diethylenglykol solvent at which the reaction solution was heated. These secondary porous particles were aggregated of numerous nanocrystalline 8~10nm diameter primary particles. ZnO spheres of various sizes(100nm~300nm) using this method by changing the amount of primary supernatant, heating rate, and the initial mole of zinc acetate dihydrate. But the uniformity was vanished when exceed zinc acetate dihydrate to 0.025mole. PL spectra consisted almost only one UV peak of these ZnO colloidal spheres, and the UV lasing phenomenon were found when the excitation intensity exceeds a threshold.
For the future, it is favorable for self-assembling close-packet periodic arrays of ZnO sphereical colloids, and possible to fabricate 3D photonic band gap structures for waveguiding and optoelectronic applications.
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