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

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题名:	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
作者:	許淑媛;Hsu,Shu-yuan
贡献者:	電機工程學系
关键词:	遠程同調穿隧效應;三個串接耦合量子點;量子傳輸;熱電
日期:	2015-07-14
上传时间:	2015-09-23 14:23:01 (UTC+8)
出版者:	國立中央大學
摘要:	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.
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