二維過渡金屬硫屬化合物 (Two-dimensional transition metal dichalcogenide, 2D -TMDC) 為一具有半導體特性之二維材料，它是由雙層的硫屬族原子如:硫，硒等 (S, Se etc.) 以共價鍵夾著一層過渡金屬原子如:鎢、鉬等 (W, Mo etc.) 所形成。其結構特性亦有如石墨烯般，層與層之間為凡得瓦力 (Van der Waals force) 鍵結，此二維材料擁有獨特的半導體能帶結構，及位於可見光波段的優異的光學特性促使眾人對其介面、表面科學、電性、光學特性等投入研究心力。在半導體元件或光電元件應用端，由此衍生出的二維材料異質結構 (2D material heterostructures) 的介面特性研究及元件發展潛力，如可調變之電子性質更是引人注目。
本文重點在於對二維材料裡，二硫化鎢 (WS2)、二硫化鉬 (MoS2) 組成之垂直堆疊 (Vertical stacking) 的異質結構，藉由高解析掃描式光電子能譜顯微術 (Scaning photoelectron microscopy/spectrroscopy)，對層狀垂直堆疊的相同材料 (WS2/MoS2與MoS2/WS2)，但具有相反順序堆疊於矽基板與金薄膜表面的進行介面能帶結構研究。另外，TMDC異質結構間的光學、振動等特性亦是我們感興趣的課題，藉由光激發螢光光譜及拉曼光譜研究兩材料間的介面間的耦合交互作用 (Interlayer coupling) ，輔以能譜結果加上文獻比較，發現在此二維材料異質結構的電荷轉移 (Charge transfer) 與自發極化結果並加以建立模型，了解此二維異質結構的介面物理與電子能帶結構等特性，相信對二維材料半導體光電元件的開發上會有所貢獻。

The discovery of the two-dimensional (2D) layered semiconductors, as transition metal dichalcogenide (TMDC), have gained interests due to their remarkable electronic and optical properties. The TMDC heterostructures offer a new platform for exploring new physics as well as future device applications. Therefore, the study of electronic structures of the TMDC heterostructures is crucial for potential usage in practical devices.
In this study, we have performed the scanning photoelectron microscopy /spectroscopy measurements to investigate the electronic structure of vertical stacked WS2/MoS2 and MoS2/WS2 heterojunctions on the Si substrate and Au film surface. We investigated the interlayer coupling effect in TMDC heterostructures via photoluminescence and Raman spectroscopy. In addition, We have determined the band alignments of two vertical stacking TMDC heterostructures- WS2/MoS2 and MoS2/WS2 by van der Waals attraction. Moreover, the spontaneous polarization model in TMDC heterostructures was established by X-ray photoelectron spectroscopy. These results and findings open up venues to creating new material systems with rich functionalities and novel physics.

摘要 I
Abstract II
誌謝辭 III
目錄 IV
圖目錄 VI
表目錄 X
第一章 緒論 1
1.1前言 1
1.2研究動機 3
第二章 文獻回顧 5
2.1 TMDCs材料特性 5
2.1.1 TMDCs晶體結構與能帶特性 5
2.1.2 TMDCs 光學及振動特性 9
2.2 TMDCs之垂直堆疊異質結構 11
2.2.1垂直堆疊異質結構之光學特性 11
2.2.2垂直堆疊異質結構之振動特性 14
2.2.3垂直堆疊異質結構之能帶特性 15
第三章 實驗儀器原理及方法 21
3.1同步輻射光源 (Synchrotron Radiation Light Source) [42, 43] 21
3.2同步輻射原理 22
3.3 X光光電子能譜術 (X-ray Photoemission Spectroscopy; XPS) 25
3.3.1 XPS基本原理 25
3.3.2能量分析儀及能量校準 27
3.3.3光電子能譜分析 29
3.4掃描式光電子顯微能譜術 (Scanning Photoelectron Microscopy & Spectroscopy; SPEM/S) [42, 54] 32
3.5光激發螢光光譜 (Photoluminescence Spectrum) 34
3.5.1 激子基本物理[56] 34
3.5.2 半導體之光激發螢光光譜 35
3.6拉曼光譜 (Raman Spectrum) 37
第四章 TMDC異質結構實驗結果分析 38
4.1實驗樣品設計 38
4.2 WS2/MoS2異質結構(Vertical heterostructures) 40
4.2.1拉曼光譜分析 40
4.2.2光激發螢光光譜分析 42
4.2.3光電子能譜分析 45
4.3 MoS2/WS2異質結構(Vertical heterostructures) 52
4.3.1拉曼光譜分析 52
4.3.2光激發螢光光譜分析 53
4.3.3光電子能譜分析 54
第五章 討論:TMDC異質介面物理 60
5.1 WS2/MoS2與MoS2/WS2介面電偶極(Interface dipoles) 60
5.2 WS2/MoS2與MoS2/WS2異質結構能帶圖 (Band Diagram) 66
第六章 結論 68
第七章 參考文獻 69

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