不同尺寸之氧化鋅量子點電子結構與電子聲子交互作用

Size dependence of electronic structures and Electron-Phonon Coupling in ZnO quantum dots

劉毓凡(Yvonne Low)

指導教授 ： 彭維鋒

淡江大學/理學院/物理學系碩士班/碩士(2008年)

https://doi.org/10.6846/TKU.2008.00806

摘要

利用X光吸收光譜(X-ray Absorption Spectroscopy, XAS)、光激發螢光光譜(Photoluminescence Spectroscopy, PL)以及拉曼光譜(Raman Spcetroscopy)來研究不同尺寸之氧化鋅量子點的電子結構與光學特性。在拉曼光譜中，第一拉曼縱向光學聲子(the first-order Raman spectra of longitudinal optical mode, 1LO)與其泛頻(overtones, 2LO)之強度比值，2LO/1LO隨著量子點的尺寸變大而增加，與電子–聲子耦合的強度有關聯。在O K-edge X光近邊吸收光譜中也有相同的結果，即O 2pπ(Iπ)與2pσ(Iσ)軌道之吸收強度比值亦隨量子點尺寸變大而增加。經由電子–聲子耦合與X光吸收近邊光譜之研究結果，推論出氧化鋅量子點的電隅極躍遷應與c軸同向。

關鍵字

結晶方向性 ； 電子-聲子交互作用 ； 拉曼光譜 ； 量子點 ； X光吸收光譜

並列摘要

The electronic structures and optical properties of various sizes of ZnO quantum dots (QDs) were studied using x-ray absorption, photoluminescence and Raman spectroscopy. The increase in the intensity ratio of the first-order Raman spectra of longitudinal optical (1LO) modes and their overtones (2LO), such as 2LO/1LO, which is related to the strength of Electron-Phonon Coupling (EPC), increased with the size of the QDs. This EPC behavior is also associated with the O K-edge x-ray absorption near-edge structure which increase with the intensity ratio of the O 2pπ(Iπ) and 2pσ(Iσ) orbitals as the sizes of the QDs increased, suggesting that the c-axis of the wurtzite ZnO QDs is the unique axis in the dipole transition.

並列關鍵字

crystal orientation ； Electron-Phonon interactions ； Raman spectra ； quantum dots ； XANES

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