拓樸絕緣體因其特殊的能帶結構及反常的物理特性，不論在物理模型的預測、材料的製備或者是材料基本特性的研究，皆引起廣大的研究熱潮。鉍系(Bi2Te3, Bi2Se3)拓樸絕緣體因其發現的時間較早更廣為利用於熱電材料上，製程技術上較為成熟，但在數奈米薄膜下的材料特性及載子傳輸過程仍有許多未知的問題有待研究。
本篇論文中，我們利用新穎的激發-探測光譜系統來探討拓樸絕緣體載子動力學及聲子傳遞的過程。首先，我們利用極低的激發光能量強度來觀察銻化鉍(Bi2Te3)薄膜從未飽和至飽和情況下的載子動力學。表面態與塊材態彼此之間的競爭行為被用來清楚地解釋材料越薄下，塊材態會逐漸主導整個動力學行為。另一方面，我們架設一套新型反射式的激發-探測光譜系統，量測硒化鉍(Bi2Se3)非激發面聲子的傳遞過程。同調光頻聲子的訊號被清楚地觀察到，證實了先前以一般反射式激發-探測光譜及理論模擬所得到的結果，也顯示了聲子於薄膜下傳遞的特性。此外，聲子的生命週期及鬆弛時間隨厚度的變化也被分析及討論。

In this thesis, carrier dynamics and phonon propagation of topological insulators are investigated using novel pump-probe technique. First, the evolution of carrier dynamics of Bi2Te3 thin films from unsaturated to saturated condition was characterized by extremely low excitation condition. The competition between surface state and bulk state was proposed to interpret the clear trend of which the bulk state will dominate the behavior as decreasing film thickness.
Regarding to the phonon propagation of topological insulator Bi2Se3 thin films, a new type of reflective pump probe which the pump and probe beam excite the film on the opposite side was buildup. The result of clear coherent phonon behavior further confirm the conclusion from typical reflective pump probe measurement. Additionally, the result indicated the nature of phonon propagation. Furthermore, thickness dependent of phonon life time and relaxation time are also discussed.

第一章 緒論 1
1.1 前言 1
1.2 研究動機 2
1.3 論文架構 3
第二章 超快雷射激發-探測光譜系統理論與拓樸絕緣體簡介 4
2.1 超快雷射激發-探測光譜系統介紹 6
2.1.1 超快雷射激發-探測光譜系統原理 7
2.1.2 超快激發-探測光譜系統架構介紹 11
2.2 系統解析度與脈衝寬度 13
2.2.1 自相關系統 15
2.2.2 系統解析度分析 21
2.3 拓樸絕緣體簡介 22
2.3.1 拓樸絕緣體之概述 22
2.3.2 拓樸絕緣體之能帶結構 24
2.3.3 三維拓樸絕緣體—硒化鉍與銻化鉍之節及能帶結構 28
2.3.4 拓譜絕緣體的應用 31

第三章 拓樸絕緣體薄膜在超低激發情況下之超快載子動力學研究 32
3.1 實驗樣品條件與參數 34
3.2 激發-探測光譜之文獻分析與研究動機 35
3.3 拓樸絕緣體的非線性飽和吸收機制 39
3.3.1 非線性飽和吸收特性及實驗架構 39
3.3.2 刀口法及雷射能量強度分析 41
3.3.3 銻化鉍(Bi2Te3)薄膜非線性飽和吸收強度分析 44
3.4 超低激發時間解析反射式激發-探測光譜系統 47
3.5 實驗結果與分析 51
3.6 結論 59
第四章 拓樸絕緣體硒化鉍(Bi2Se3)薄膜聲子的單方向傳播及其超快載子動力學研究 60
4.1 拓樸絕緣體薄膜之聲子震盪行為 62
4.2 實驗數據回顧 66
4.2.1 硒化鉍(Bi2Se3)薄膜的反射式激發-探測光譜(OPOPR)實驗數據 67
4.2.2 硒化鉍(Bi2Se3)薄膜的穿透式激發-探測光譜(OPOPT)實驗數據 70
4.2.3 OPOPR及OPOPT實驗數據總結與分析 75
4.3 拓樸絕緣體薄膜之聲子震盪單方向傳播模擬 77
4.4 新型反向探測時間解析反射式激發-探測光譜系統 81
4.5 實驗樣品條件與參數 85
4.6 實驗結果與分析 87
4.6.1 反向探測激發-探測光譜(BOPOPR)的瞬時反射率變化光譜分析 87
4.6.2 硒化鉍薄膜內部載子特性分析 94
4.7 結論 97
第五章 結論與未來展望 98
5.1 結論 98
5.2 未來展望 99
參考文獻 100

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