單一半導體量子點與塊材半導體最大的不同是它具有優秀量子侷限效應，使的量子點中形成激子具有可隨量子點大小控制的不同能隙，因此具有可控制的吸收及螢光波長。除了單激子外，我們另外可以觀察到單一半導體量子點中的多激子行為表現。本論文中，利用單分子螢光測量來探討單一CdSe/ZnS 半導體量子點形成多激子時與激發光強度相關的程度。
在逐漸遞增的激發光強度下，量子點的螢光生命曲線以及光子反成串行為顯示出會有比較快速的螢光生命曲線，這代表的意義就是來自量子點中多激子的鬆弛行為，並結果顯示出要從激子狀態中產生多激子會有一個能階上的門檻值。在低強度激發光下，可以看到光子反成串行為及近乎單一指數鬆弛的螢光生命曲線，然後當激發光強度提高超越門檻值時，同一顆量子點上會出現額外快速衰減的螢光生命曲線及光子成串行為，明白的指示出多階段的輻射鬆弛過程。
除此之外，我們調變線性偏極化光去激發量子點樣品。結果顯示多激子的emission dipole 與單激子的情況相同，會有一個對稱c 軸的二維 transition dipole bright plane。然而在absorption dipole 方面，多激子則具有與單激子不同的激發電場偏振的關聯。

The major difference between semiconductor quantum dots and bulk semiconductors is in the quantum confinement effect. It results the controllable exciton’s absorption and emission spectra by tuning the size of the quantum dot. Moreover, multi-exciton states are reported to be observed in the highly symmetric quantum dot systems. In this dissertation, we use the single molecule fluorescence measurement to study the power dependence of multi-exciton state in single CdSe/ZnS semiconductor quantum dots.
At low excitation fluence, anti-bunching behavior, and nearly single exponential relaxation dynamics are observed. By increasing the laser power, bi-exponential fluorescence decay dynamics as well as bunching behaviors from the same QD indicate the fast PL dynamics due to the relaxation from multi-exciton. The results indicate certain threshold
energy level for multi-exciton generation. In addition, the multiple step cascade radiative relaxation processes are observed.
Besides, we modulate linear polarization light to study the excitation orientation dependence. The results indicate the emission dipole of multi-exciton is similar to the single exciton, having a two dimensional
transition dipole plane with c-axis symmetry. However, the absorption dipole of multi-exciton exhibits different orientation dependence from the single exciton.

總目錄
中文摘要
英文摘要
致謝
總目錄
圖目錄
表目錄
符號表
第一章 緒論.............................................................................................1
第二章 太陽能電池的效率提升.............................................................4
2-1 節 太陽能電池的發展..............................................................4
2-2 節 熱力學理論下太陽能電池的終極效率..............................5
2-3 節 單一接面太陽能電池裡的損失..........................................7
2-4 節 第三代太陽能電池.............................................................9
2-5 節 Tandem solar-cell.................................................................11
2-6 節 Hot carrier solar-cell............................................................14
2-7 節 一個光子產生多電子與電洞對.........................................15
第三章 多激子的螢光量測……………………………………………24
3-1 節 半導體…………………………………………………….24
V
3-2 節 量子點簡介.........................................................................27
3-2.1 節 量子點.......................................................................27
3-2.2 節 量子點的特性及應用................................................29
3-3 節 半導體量子點.....................................................................33
3-4 節 激子.....................................................................................34
3-4.1 節 激子的種類.................................................................34
3-4.2 節 自由激子的鍵結能及半徑..........................................36
3-4.3 節 高密度下的自由激子..................................................39
3-5 節 半導體量子點中的多激子...................................................41
3-5.1 節 多激子產生的機制......................................................42
3-5.2 節 單一量子點中的多激子鬆弛機制.............................50
第四章 螢光原理和實驗架構、樣品.....................................................53
4-1 節 螢光簡介...............................................................................53
4-1.1 節 螢光的機制..................................................................53
4-1.2 節 螢光量子效率 ( Fluorescence Quantum Yield )........57
4-1.3 節 螢光非等向性 ( Fluorescence Anisotropy ) ..............58
4-1.4 節 螢光生命期 (Fluorescence Decay Lifetime ) ...........58
4-2 節 單分子螢光量測方式.........................................................59
VI
4-3 節 實驗架構............................................................................61
4-4節 實驗樣品.............................................................................63
4-5節 半導體量子點的光物理特性.............................................64
第五章 實驗方法及步驟.......................................................................68
5-1 節 樣品準備..............................................................................68
5-2 節 實驗步驟..............................................................................69
第六章 實驗結果與討論.......................................................................77
6-1單一量子點的螢光量測結果.....................................................77
6-2 單一量子點與激發光功率的相關行為....................................79
6-3 多激子的螢光生命期................................................................81
6-4 多激子的光物理特性.................................................................86
第七章 結論與未來展望........................................................................94

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