量子點奈米線在室溫下之ZT值優化;Optimizing thermoelectric efficiency of quantum dot nanowires at room temperature

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/77588

Title:	量子點奈米線在室溫下之ZT值優化;Optimizing thermoelectric efficiency of quantum dot nanowires at room temperature
Authors:	黃謙羽;Huang, Chien-Yu
Contributors:	電機工程學系
Keywords:	量子點;奈米線;ZT;室溫;Quantum dot;nanowire;ZT;room temperature
Date:	2018-07-09
Issue Date:	2018-08-31 14:49:11 (UTC+8)
Publisher:	國立中央大學
Abstract:	本論文探討量子點奈米線系統ZT值在室溫下的優化。我們考慮的系統為量子點奈米線和金屬電極的接面系統，該系統可以利用量子力學的二次量化算符來建構，除此之外，系統的熱電係數可以利用格林函數來計算。我們發現在室溫k_B T=25meV，且量子點能階和電極費米能階差Δ=60meV時，可以得到最佳化的功率因子。這優化條件在電子躍遷強度與溫度的比值，滿足t_c⁄(k_B T)≤0.5的情況，且和量子點的數量無關，也就是說，PF和奈米線長度幾乎無關。在量子點間的強躍遷強度(即弱的電子庫倫力)情況，我們可以在奈米線直徑D=3nm的條件下，得到室溫k_B T=25meV，ZT>3。;This thesis investigates the optimization of figure of merit of quantum dot nanowire junction system connected to metallic electrodes at room temperature. The Anderson model is used to simulate the system Hamiltonian. The thermoelectric coefficients are calculated in the framework of Green’s functions. We have obtained the maximum power factors at room temperature when Δ/k_B T=2.4 and Γ=2t_c, where Δ=E_0-E_F is the energy difference between the QD energy levels and Fermi energy of electrodes. Γ and t_c denote, respectively, the electron tunneling rates and hopping strengths. We note that power factor is almost independent on the QD numbers. ZT>3 can be achieved for a Si/Ge QD superlattice nanowire with diameter D=3nm.
Appears in Collections:	[Graduate Institute of Electrical Engineering] Electronic Thesis & Dissertation

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