奈米結構化半導體之新奇特性

Novel properties of nanostructured semiconductors

林夏玉(Hsia Yu Lin)

指導教授 ： 陳永芳

國立臺灣大學/理學院/物理研究所/博士(2006年)

https://doi.org/10.6342/NTU.2006.01458

摘要

為了能夠充分地瞭解奈米結構半導體的特性，我們研究其中的形貌、結構與光學特性之間的關連，除了研究他們的基本特性、發展數種方法來增加這些奈米結構的發光強度，並探討這些發光增強的機制，我們也利用陰極螢光光譜研究奈米材料的特殊性質，這些研究材料包含氧化矽奈米顆粒、硫化鎘包金奈米顆粒、氧化鋅奈米線、氮化鎵鋁三元化合物與銦化鎵量子點，我們使用螢光光譜、X-ray能量分散式光譜與陰極螢光光譜探討他們的能帶與缺陷的發光和成分，與他們彼此之間的對應關係，並研究可以增強或是抑制這些材料發光的方法：對於氧化矽奈米顆粒而言，利用二倍頻表面電漿共振可使得氧化矽包覆金粒子奈米顆粒缺陷發光強度達一千倍；硫化鎘包金的奈米粒子則呈現能帶與缺陷的發光增強四十倍的現象；在氧化鋅奈米線表面鍍上奈米金顆粒不但可以抑制缺陷發光，並可以加強能帶的發光強度至一千倍，我們認為表面電漿共振所引起的能量轉移是造成這些半導體產生發光變化的主因；氮化鎵鋁三元化合物薄膜在長晶過程中會產生的成分變化可以直接用陰極螢光光譜量測出，砷化銦—砷化鎵自組裝量子點結構在不同間隔層厚度下表現出不同的發光性質，受到應力的作用，量子點的尺寸、位置也會改變。

關鍵字

半導體 ； 光學

並列摘要

To have a complete understanding of nanostructured semiconductors, in this thesis we emphasize the strong correlation between morphological, structural, and optical properties. Besides the investigation of basic physical properties, several methods have been developed to enhance optical properties of nanostructured semiconductors, and the corresponding mechanisms have also been established. In addition, the technique of selective wavelength mapping for the characterization of nanomaterials based on conventional cathodoluminescence (CL) has been developed. The studied nanomaterials include SiOx nanoparticles, ZnO nanowires, CdS nanoparticles, AlGaN epifilms, and self-assembled InAs quantum dots. Photoluminescence, energy dispersive X-ray spectrum, cathodoluminescence were employed to explore the band and defect emissions, compositions, and relations among them. Several methods have been designed to suppress or enhance luminescence properties. For SiOx nanoparticles, a kind of MCM-41 mesoporous, embedding of gold nanoparticle can greatly enhance the defect emission by one thousand times. It is discovered that second harmonic surface plasmon resonance can be used to enhance optical properties of nearby nanomaterials. For CdS nanoparticles, Au-CdS core-shell nanostructures reveal 40 times enhancement in the emission intensity. For ZnO nanowires coated with metal nanoparticles, we found that the defect emission can be suppressed to the noise level, while the band gap emission can be greatly enhanced. The intensity ratio of the band gap and defect emissions can be improved by up to one thousand times. Surface plasmon resonance induced energy transfer in nanocomposites is used to interpret the giant enhancement. With the newly developed CL image technique, direct evidence of the compositional pulling effect in AlGaN epifilms shows gradual variation of Al along the growth direction. Finally, self-assembled InAs quantum dots reveal various properties with different spacer layer. The dot sizes are strongly correlated with the stain induced by the spacer layer.

並列關鍵字

semiconductor ； optics

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