本論文主要是使用APSYS (Crosslight Software Inc.)數值模擬軟體，以模擬分析及理論計算的方法，去研究以三族氮化物為基礎材料之穿隧接面與串接式發光二極體的結構設計及物理機制。
第一章部分，簡介氮化物發光二極體的發展里程碑及市場概況，並詳加描述氮化物材料系統獨有之極化效應相關原理與計算 (自發極化和壓電極化)，以及efficiency droop現象在氮化物發光二極體所涵蓋的問題與各研究團隊提出的研究成果及解決方式，最後介紹氮化物穿隧接面及串接式發光二極體的原理與應用。
第二章部分，介紹APSYS數值模擬軟體在發光二極體中所使用之物理模型與本研究所使用的相關材料參數，例如：能帶間隙的計算、輻射和非輻射複合、漂移及擴散模型、量子井中光子的產生、以及interband穿隧模型。
第三章部分，利用極化工程設計穿隧接面，在PN重摻雜層插入一層本質氮化銦鎵層，探討中間本質氮化銦鎵的銦含量及兩側PN重摻雜層的摻雜濃度在負偏壓之下，各結構穿隧電流密度之大小，並在中間本質氮化銦鎵及兩側PN重摻雜層提出合理的銦含量及摻雜濃度。隨後，以氮化鋁鎵/氮化銦鎵多層交替的結構取代單層的氮化銦鎵，模擬結果顯示，通過適當的極化工程結構設計，利用氮化鋁鎵/氮化銦鎵多層交替的結構可以獲致低電阻率和優異穿隧特性的穿隧接面。
第四章部分，詳細介紹了本論文中所參考的單顆藍光和綠光發光二極體的結構，合理調整模擬參數和實驗數據以達到最大的一致性。之後，使用穿隧接面垂直堆疊多個綠光發光二極體集成在單顆元件中，而串接式綠光發光二極體通過在相對較低的電流密度下工作，與相同輸出功率水平的單個LED對應物相比，具有抑制的歐傑複合和高量子效率。
第五章部分，簡化4-1章節的藍光及綠光發光二極體結構，使用穿隧接面堆疊氮化銦鎵兩個綠光及一個藍光發光二極體，結合磷化鋁鎵銦黃光及紅光發光二極體以獲致高演色性，並利用電流的改變而調配出不同的色溫之白光發光光源。接著使用穿隧接面堆疊氮化銦鎵五個不同波長發光二極體，使其達半高全寬約90 nm之寬頻譜設計。最後，進一步改善寬頻譜發光二極體的結構，設計出只需堆疊三個氮化銦鎵發光二極體即可達到半高全寬為110 nm的單片寬頻譜發光二極體結構。
第六章部分，統整前述的研究成果。最後，展示單片無螢光粉全彩光串接式發光二極體之初步模擬成果。本文進行的數值模擬結構設計，期望能為商用發光二極體提供創新的技術及實現新一代的性能。

The work in this dissertation is aimed towards understanding and improving the design of III-nitride based tunnel junctions and tunnel-junction light-emitting diodes (LEDs) through physical modeling and numerical simulation approach by a commercial TCAD simulation tool APSYS.
In chapter 1, brief introduction to the developmental milestones, applications, and potential markets of III-nitride LEDs is provided. Next, two characteristics of nitride-based devices of the droop and polarization effects are unique to this material system. The principles and calculations of spontaneous and piezoelectric polarization, and the issues and solutions of efficiency droop will be explained. Finally, the principles and applications of III-nitride tunnel junctions and tunnel-junction LEDs are introduced.
In chapter 2, fundamental physical mechanisms and material parameters of III-nitride tunnel junctions and tunnel-junction LEDs used in this dissertation are introduced. The physical mechanisms under study include bulk band structure, radiative and non-radiative recombinations, drift-diffusion model, photon generation in QWs, and interband tunneling.
In chapter 3, the use of undoped InGaN material between the heavily doped n-GaN and p-GaN layers with various indium compositions and doping concentrations is analyzed. Afterwards, the structural optimization and polarization engineering of InGaN/AlGaN multi-layer tunnel junctions are systemically investigated. The simulation results demonstrate that, with appropriate structural designs, InGaN/AlGaN multi-layer tunnel junctions via polarization engineering, low-resistivity and excellent tunneling characteristics can be achieved.
In chapter 4, layer structures of the reference single blue and green LEDs used in this dissertation are introduced in detail. The simulation parameters and experimental data can be reasonably adjusted to achieve maximum consistency. Then, more green LEDs are grown in a continuous vertical stack using a tunnel junction to integrate the multiple LEDs in a single device. The tunnel-junction green LED can be operated at relatively low current density that possesses suppressed Auger recombination and high quantum efficiency when compared with its single LED counterpart at the same level of output power.
In chapter 5, the goal is to simplify the blue and green LED structures of Section 4-1. Two unit green LEDs and one unit blue LED are stacked with the use of tunnel junctions. The blue/green dual-color tunnel-junction LED under various currents combined with AlGaInP-based yellow and red LEDs under fixed current may be used to achieve high CRI white light emitter. Next, five different wavelength InGaN LEDs are stacked to achieve broad-band spectrum with FWHM of around 90 nm. Finally, design of broad-band spectrum LEDs is further improved. A simulated monolithic tunnel-junction LED is demonstrated with three unit stacked LEDs with a wide FWHM of approximately 110 nm.
In chapter 6, summary of the dissertation is provided and some future work expectations are proposed. The preliminary simulation results of the monolithic stacked phosphor-free full-color tunnel-junction LED is demonstrated at the end of dissertation.

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