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研究生: 許淑媛
Shu-yuan Hsu
論文名稱: 三個串接耦合量子點系統的遠程同調穿隧 效應對電流及電子熱流的影響之分析
Long-distance coherent tunneling effect on the charge and heat currents in serially coupled triple quantum dots
指導教授: 郭明庭
Ming-ting Kuo
口試委員:
學位類別: 碩士
Master
系所名稱: 資訊電機學院 - 電機工程學系
Department of Electrical Engineering
論文出版年: 2015
畢業學年度: 103
語文別: 中文
論文頁數: 53
中文關鍵詞: 遠程同調穿隧效應三個串接耦合量子點量子傳輸熱電
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  • 在本論文裡,結合了extened Hubbard 模型和Anderson 模型說明在遠程同
    調穿隧(Long-distance coherent tunneling ,LDCT) 效應下,三個量子點串接
    耦合在一起並且左右端連接電極時產生的電流與熱流,並且採用凱帝旭-格林函
    數方法詮釋串接耦合量子點的傳輸行為。利用有效質量理論計算半導體量子點彼
    此間的電子庫倫交互作用力、電子躍遷強度以及偏壓相依的雙量子點能階。隨著
    雙量子點間距的增加,量子點間的耦合強度會以指數型式變弱,因此電流和電子
    熱流值隨之變小。若在兩個量子點之間嵌入另一個量子點,則外側量子點的耦合
    在遠程同調穿隧(LDCT)效應下將增強。因此可藉由調控中間量子點的能階來改變
    外側量子點系統的傳輸特性。此外,在非對稱能階的情形下更可明顯看出熱整流
    效應存在於三個量子點的系統中。


    In the thesis, combined the extened Hubbard and Anderson models to illustrate
    the effect of long-distance coherent tunneling(LDCT) on charge and heat currents in
    serially coupled tripled quantum dots(SCTQDs) connected to left and right electrodes.
    The transmisssion coefficient of quantum dots in columb blockage regime can be
    calculated by Keldysh-Green’s function technique. The physical parameters including
    electron Coulomb interactions, electron hopping strengths, and bias-dependent
    quantum dot energy levels are calculated in the framework of effective mass theory
    for semiconductor TQDs. The interdot coupling strength decreases exponentially with
    the separation between QDs. Therefore, the charge and heat currents will become
    insignificant. If embedded another QD in the middle of two QDs, the effect of LDCT
    on the coherent of outside QDs can be robust. It’s possible to change the transmission
    characteristics by tuning the energy level of the middle QD. In addition, it is shown
    that prominent heat rectification behavior can exist in the TQD system with
    asymmetrical energy levels.

    摘 要.............................................................................................................................. I ABSTRACT .................................................................................................................. II 致謝.............................................................................................................................. III 目錄.............................................................................................................................. IV 圖目錄.......................................................................................................................... VI 第一章 導論.................................................................................................................. 1 1-1 前言 .............................................................................................................. 1 1-2 熱電簡介及歷史 .......................................................................................... 2 1-3 三個量子點的串接耦合(Serilly coupled triple quantum dots, SCTQDs) 5 1-4 研究動機 ...................................................................................................... 6 第二章 系統模型........................................................................................................ 7 2-1 串接耦合量子點系統 ..................................................................................... 7 2-3 物理參數的探討 .......................................................................................... 10 第三章 線性響應區間的熱電分析............................................................................ 15 3-1 熱電特性 ...................................................................................................... 15 3-2 遠程同調穿隧效應(LDCT)分析 ................................................................. 16 3-3 庫倫交互作用力對於熱電係數的影響 ...................................................... 22 V 3-4 電子躍遷強度對於熱電係數的影響 .......................................................... 24 第四章 非線性響應區間的電流及熱流分析............................................................ 26 4-1 庫倫交互作用力與遠程同調穿隧(LDCT)效應之穿隧電流分析 ............. 26 4-2 穿隧率與LDCT 效應之穿隧電流分析 ...................................................... 29 4-3 電子躍遷強度與LDCT 效應之電流分析 .................................................. 31 4-4 遠程同調穿隧效應(LDCT)效應對電子熱流的影響 ............................... 33 第五章、結論.............................................................................................................. 38 參考文獻...................................................................................................................... 39

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