利用X-ray吸收譜研究銪元素摻雜於氧化鋅奈米線

X-ray absorption spectroscopic studies of Eu-doped ZnO nanowires

黃偉倫(Wei-Lun Huang)

指導教授 ： 彭維鋒

淡江大學/理學院/物理學系碩士班/碩士(2009年)

https://doi.org/10.6846/TKU.2009.00864

摘要

本論文主要以X光吸收光譜實驗研究銪元素摻雜於氧化鋅奈米線的電子與原子結構。實驗包含室溫時以法線夾角37°入射樣品之X光吸收近邊緣結構(X-ray absorption near edge structure，XANES)、延伸X光吸收精細結構(Extended x-ray absorption fine structure，EXAFS)及樣品橫切面的掃描式光電子顯微能譜(Scanning Photoemission Microscope, SPEM)。由O K-edge XANES的吸收峰減弱與變寬與對照Eu L3-edge XANES，可推論樣品O 2p與Eu 5d有鍵結產生。EXAFS結合非線性最小方陣模擬(Nonlinear least squares fitting)電腦程式FEFFIT分析，顯示Eu可能會取代Zn或者填入Zn的空缺(vacancy)，但並沒有改變ZnO 之Wurtzite結構。SPEM可看到，靠近費米面的地方有Eu 4f 的貢獻。摻雜Eu使得ZnO表面的缺陷增加，因而增強了Eu-doped ZnO nanowire 的光激螢光的發光效率。

關鍵字

銪元素摻雜於氧化鋅 ； 氧化鋅 ； 銪 ； 吸收譜

並列摘要

X-ray absorption near-edge structure (XANES), extended x-ray absorption fine structure (EXAFS), and Scanning photoemission microscope (SPEM) measurements were used to observe the influence of Eu-doped zinc oxide (ZnO) nanowires and to understand the unoccupied as well as occupied states of electronic structure and locally fine structure.
The O K-edge XANES spectrum showed a broad and lower intensity compared to the undoped sample, which is interpreted as a rehybridization of the O2p derived state with the Eu5d state. This process lowers the energy of O2p states and enhances its occupancy by electrons from europium.
EXAFS have revealed that Eu3+ ions maybe replaced Zn2+ in the Zn site, or filled-in in the Zn-site vacancies, but did not change the Wurtzite structure of host materials. The process thereby increases defects in the surface resulting to the enhanced PL of the Eu-doped ZnO nanowires.

並列關鍵字

Eu-doped ZnO ； ZnO ； Eu ； X-ray absorption

參考文獻

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