單電子電晶體耦合量子點的負微分電導效應; Negative differential conductance effect of the parallel coupled Quantum Dots

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Title:	單電子電晶體耦合量子點的負微分電導效應;Negative differential conductance effect of the parallel coupled Quantum Dots
Authors:	王嘉豪;Jia-hao Wang
Contributors:	電機工程研究所
Keywords:	單電子電晶體;穿隧電流;single electron transistors;tunneling current
Date:	2008-06-19
Issue Date:	2009-09-22 12:08:05 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本論文是利用格林函數，系統化的探討單電子電晶體的穿隧電流頻譜。首先在一階系統裡，分析了內階庫倫交互作用力所造成的影響；由於庫倫阻斷效應，使穿隧電流呈現出庫倫階梯以及庫倫震盪的現象。我們還分析了穿隧率改變對電流頻譜所造成的影響，穿隧率的改變會影響電流頻譜上各個通道的強弱。在二階系統裡，由於能階之間會互相影響，所以加入了外階庫倫交互作用力這項參數；二階系統的電流頻譜，會受到內階庫倫交互作用力與外階庫倫作用力的共同作用。在經過一連串的分析之後，我們整理出了影響能階裡各個通道強弱的因素。而最後探討了在雙量子點系統裡，負微分電導的成因，發現到負微分電導的產生，和量子點左右穿隧率的比例息息相關，只有當量子點B為殼層填充時，才觀察的到負微分電導。　　Tunneling current of single-electron transistor is systematically investigated by using the Keldysh Green function method in this thesis. For one energy level case, the Coulomb staircase and Coulomb oscillation of tunneling current with respect to the applied bias and gate voltage arise from intralevel electron Coulomb interaction. We also found that tunneling rate ratio significantly influences the tunneling current spectrum. For two energy level case, the interlevel Coulomb interactions as well as intralevel Coulomb interactions exist remarkable effect on the tunneling current. Finally, we study the tunneling current through paralleled two quantum dot system. The tunneling current shows the negative differential conductance (NDC) behavior resulting from the interdot Coulomb interactions. Such a NDC effect exists in the quantum dot with shell-filling condition.
Appears in Collections:	[Graduate Institute of Electrical Engineering] Electronic Thesis & Dissertation

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