為了得到良好的熱整流特性，許多科學家在低維度的系統下研究熱二極體。為了能作為實際應用，本論文探討了非線性響應下二維量子點超晶格奈米線(SLNWs)陣列的熱二極體性質。我們使用非平衡態格林函數的方法研究連接電極的超晶格奈米線陣列的傳輸特性。驗證了在不對稱量子點能階排列的超晶格奈米線陣列中可以觀察到電子熱整流現象。超晶格奈米線陣列的熱二極體特性歸因於隨著溫差的方向而有大小變化的傳輸係數。電子熱流分別在順向溫度偏壓和逆向溫度偏壓顯現了熱導體和熱絕緣體的特徵。本論文闡明了二維量子點系統中y方向電子躍遷強度對熱二極體系統的影響。我們也發現到熱離子輔助穿隧程序(TATP)對觀察到本系統的電子熱整流效應有著顯著的影響。

In order to get a high heat rectification ratio, many scientists studied heat diodes in low-dimensional systems. For realistic applications , we investigated the nonlinear electron heat transport in 2-D quantum dot (QD) superlattice nanowires (SLNWs) arrays in this thesis. The nonequilibrium Green-functions technique is used to study the transport properties of an SLNW array junction coupled to the metallic electrodes. It is demonstrated that the electron heat rectification can be observed in an SLNWs array with asymmetrical alignment of energy levels in QDs. The SLNWs arrays show the functionality of heat diodes, which is mainly attributed to a transmission coefficient with a temperature-bias direction dependent characteristic. Electron heat current shows the features of thermal conductors and thermal insulators under the forward temperature bias and reverse temperature bias, respectively. This thesis clarifies the effects of the electron hopping strength in the y direction on electron heat currents. We also find the thermionically-assisted tunneling procedure plays a remarkable role in observing electron heat rectification of such a junction system.

[1] M. Terraneo, M. Peyrard, and G. Casati, “Controlling the energy flow in Nonlinear lattices: A model for a thermal rectifier” ,Phys. Rev. Lett. 88, 094302 (2002).
[2] B. W. Li, L. Wang, and G. Casati, “Thermal diode: Rectification of heat flux” , Phys.
Rev. Lett. 93, 184301 (2004).
[3] J. H. Lan and B. W. Li, “Size-dependent thermal conductivity of nanoscale semiconducting systems”, Phys. Rev. B 74, 214305 (2006).
[4] S. Pal and I. K. Puri, “Thermal rectification in a polymer-functionalized single-wall carbon nanotube” , Nanotechnology 25, 8 (2014).
[5] X. Cartoixa, L. Colombo, and R. Rurali, “Thermal Rectification by Design in
Telescopic Si Nanowires” , Nano Lett. 15, 8255 (2015).
[6] Y. Li, X. Y. Shen, Z. H. Wu, J. Y. Huang, Y. X. Chen, Y. S. Ni, and J. P.
Huang, “Temperature-Dependent Transformation Thermotics: From Switchable Thermal Cloaks to Macroscopic Thermal Diodes” , Phys. Rev. Lett. 115, 195503 (2015).
[7] C. L. Chiu, C. H. Wu, B. W. Huang, C. Y. Chien and C. W. Chang, “Detecting thermal rectification” ,AIP ADVANCES 6, 121901 (2016).
[8] C. R. Otey, W. T. Lau, and S. H. Fan, “Thermal Rectification through Vacuum” , Phys. Rev. Lett. 104, 154301 (2010).
[9] D. M.-T. Kuo and Y. C. Chang, “Thermoelectric and thermal rectification properties of
quantum dot junctions” ,Phys. Rev. B 81, 205321 (2010).
[10] B. Li, L. Wang, and G. Casati, “Negative differential thermal resistance and thermal transistor” ,Appl. Phys. Lett. 88, 143501 (2006).
[11] L. Wang and B. Li, “Thermal Logic Gates: Computation with Phonons”, Phys. Rev. Lett. 99, 177208 (2007).
[12] C. Starr, “The Copper Oxide Rectifier”, J. Appl. Phys. 7, 15 (1936).
[13] C. W. Chang, D. Okawa, A. Majumdar, and A. Zettl, “Solid-State Thermal Rectifier”, Science 314, 1121 (2006).
[14] K. Ito, K. Nishikawa, H. Iizuka, and H. Toshiyoshi, “Experimental investigation of radiative thermal rectifier using vanadium dioxide” ,Appl. Phys. Lett. 105, 253503 (2014).
[15] M. J. Martinez-Perez, A. Fornieri, and F. Giazotto, “Rectification of electronic heat current by a hybrid thermal diode” , Nature Nanotech. 10, 303 (2015).
[16] Y. Guerfi and G. Larrieu, “ Vertical Silicon Nanowire Field Effect Transistors with Nanoscale Gate-All-Around” ,Nanoscale Research Letters 11,210 (2016).
[17] H. Haug and A. P. Jauho, “Quantum Kinetics in Transport and Optics of Semiconductors” (Springer, Heidelberg,1996).
[18] Y. Meir and N. S. Wingreen, “ Landauer formula for the current through an interacting electron region” ,Phys. Rev. Lett. 68, 2512 (1992).
[19] D. M. T. Kuo, “Thermoelectric and electron heat rectification properties of quantum dot superlattice nanowire arrays” , AIP Advances 10, 045222 (2020).
[20] B. H. Teng, H. K. Sy, Z. C. Wang, Y. Q. Sun, H. C. Yang, “Exact analytical solution to the electronic transport in an N-coupled quantum dot array” , Phy. Rev. B 75, 012105 (2007).
[21] Y. Liu, Y. S. Zheng, W. J. Gong, W. H Gao and T. Q. Lu, “Electronic transport through a quantum dot chain with strong dot-lead coupling” ,Phys. Lett. A 365, 495 (2007).
[22] M. Hu and D. Poulikakos, “Si/Ge Superlattice Nanowires with Ultralow Thermal Conductivity” , Nano. Lett. 12, 5487 (2012).
[23] D. M. T. Kuo, and Y. C. Chang, the proceding of NMDC 2018 Portland.