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研究生: 鍾佳民
Chung, Chia-min
論文名稱: 半導體量子點的磁光性質
Magneto-Optical Properties of a semiconductor dot or shell
指導教授: 盧炎田
Lu, Yan-Ten
學位類別: 碩士
Master
系所名稱: 理學院 - 物理學系
Department of Physics
論文出版年: 2007
畢業學年度: 95
語文別: 英文
論文頁數: 55
中文關鍵詞: 量子點
外文關鍵詞: quantum dot
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  • 由於半導體量子點與環境材料中的界面可能存在著最低
    能態,而使的受激發的電子與電洞被束縛在如球殼的界面
    中,而非如球體的量子點中。我們分別計算了被束縛在球位
    能與球殼位能障礙的中的電子與電洞在磁場中的能階,並由
    此計算出其躍遷能量。我們發現在同樣的能量尺度下在球殼
    位能中的能階與球位能中比起來彼此較為接近,且隨著磁場
    上升的較快,這使得能階之間產生了非常多的交叉,同樣的
    這些交叉也發生在躍遷能量中,有些交叉在球位能中並不容
    易看到。我們也計算了其躍遷強度,並發現在球殼位能中能
    量最低的幾個躍遷的躍遷強度會隨著磁場有先下降再稍微
    上升到一個穩定值的現象,而在球位能中其躍遷強度只會下
    降而趨近於一個穩定值。

    It is possible that there exists some interface states with
    lowest energy comparing to the energy states contributed by
    quantum dot material and environment material, and thus the
    electrons and holes might be confined in interface, which is a region of spherical shell, but not in quantum dot which is a region of ball. We calculated the energy levels of an electron or hole confined in a ball-like or shell-like potential barrier in magnetic field, and calculated their transition energies. We found that in same scale the energy levels in shell potential are closer to each other and increase with magnetic field faster than which in sphere potential, and therefore cause many crossings in
    energy levels and in transition energies. Some crossings of
    shell potential not appear in sphere potential in our computation. We also calculate the transition strength and found that, some strengths of lowest transition energies in shell potential will decrease rapidly and then a little increase to a terminal value with increasing magnetic field; in sphere potential the transition strengths of lowest energies only decrease and approximate to a terminal value when magnetic field increase.

    Chapter 1                       1 Introduction       1 1.1 Potential applications of quantum dots 1 1.2 Basic structure of quantum dot     2 1.3 Properties of quantum dots          2 1.4 Effective mass model for quantum dots confinement 3 1.5 Model for spherical shell 3 1.6 Organization of this thesis 4 1.7 Directions for further research 4 Chapter 2 5 Model of Semiconductor Quantum Dot 5 2.1 Band gap of semiconductor 5 2.2 Band discontinuity in a heterostructure 5 2.3 Model of a quantum dot 6 Chapter 3 9 A Sphere or Shell Dot 9 3.1 An electron in a sphere potential well 9 3.2 An electron in a shell potential well 12 CHAPTER 4 17 Effects by Magnetic Field 17 4.1 Hamiltonian in constant and uniform magnetic field 17 4.2 Scaling 20 4.3 Approximation by perturbation method 25 4.4 Approximation by expanding wavefunctions 30 4.5 A hole in a sphere or shell potential well in a magnetic field 34 CHAPTER 5 35 Numerical Analysis 35 5.1 Energy levels without magnetic field 35 5.2 Energy versus magnetic field computed by perturbation method 37 5.3 Energy versus magnetic field computed by expanding wavefunction 39 5.4 Transition energy versus magnetic field 44 5.5 Transition strength versus magnetic field 49

    Kittel, Introduction solid state physics (8th ed.). (Wiley, USA, 2005)
    G. B. Arfken and H. J. Weber, Mathematical Methods for Physicists (5th ed.). (Harcourt, New York, 2001).
    Richard L. Burden and J. Douglas Faires, Numerical Analysis (7th ed). (Brooks/Cole, US, 2001)
    Stephen Gasiorowicz, Quantum Physics (3rd ed). (Wiley, USA, 2003)

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