本論文為設計發光二極體的電極形狀，幫助電流均勻擴散。其均勻電流的目的為避免元件高熱與增加主動層的使用效率。本論文所實驗的樣品為氮化鎵發光二極體，其基板材質為藍寶石。藍寶石的導電特性極差，導致製程需要把 N 型與 P 型電極製作在同一側上，造成電流在流動時會有聚集的現象。本實驗所設計的電極形狀，目的在於避免電流聚集，達到電流均勻擴散。
研究主要分為兩階段，第一階段是利用 COMSOL 模擬軟體，去作發光二極體的電流分佈模擬。先以期刊和論文資料中的數據和電極形狀去作模擬，並驗證是否和文獻資料吻合，以證實模擬的可信度，再設計出均勻度高的電極圖形。
第二階段是以第一階段所設計的圖型，分成三組逐步去實作。第一組為缺乏透明導電層的發光二極體，其目的在於驗證製程步驟是否可行，並校正模擬參數。從模擬所計算出的比值，其大小比與發光強度的大小比相同，證明模擬與實作的吻合。第二組加入了透明導電層，其發光強度大小比與模擬計算出的比值大小比有差異，推論其原因為小面積的發光二極體，其出光面積的影響較大。第三組為
大面積的發光二極體，其電極圖型成功的幫助電流擴散，並在光強度上提升了21%。模擬所計算出的電流密度分佈，其趨勢跟出光強度相符。

In this thesis, we design electrode shape of light emitter diode (LED) to help the current diffusing uniformly. The purpose of the uniform current is to avoid the waste heat from the devices and enhance the efficiency of active region. The LED samples adopted in this study are GaN base materials grown on sapphire. The P-N electrodes must be processed on the same side since the poor conductivity of sapphire. The same side P-N electrode will results in current crowding phenomena. We design special electrode shapes to make the current diffuse uniformly and reduce the current crowding phenomena.
First, we use COMSOL simulation software to simulate the current spreading between the electrodes. We adopt the same parameters from the reference papers to confirm the reliabilities of the simulation. Then we simulate several electrode shapes with highly uniform current spreading.
Second, we use the simulation results to fabricate electrode on chips. The first set is LED without transparent conductive layer. This set is to confirm whether the fabrication processes is feasible and adjust the simulation parameters at the same time.
The second set is LED with transparent conductive layer. The experimental emission intensity has deviation from the simulation results. We deduce the emission intensities
from smaller LED chip size will have great influence on illumination surface. The third set is electrodes fabricated on large size LED chip. The electrode patterns successfully enhance the uniformity of current spreading, and enhance the output light
intensity of 21%. The current density distribution trend from simulation is matched with the illumination intensities.

論文審定書................................................................................................................... i
誌謝............................................................................................................................. iii
中文摘要..................................................................................................................... iv
英文摘要....................................................................................................................... v
目錄............................................................................................................................. vi
圖次............................................................................................................................ vii
表次............................................................................................................................... x
第一章 緒論................................................................................................................. 1
1-1 背景與研究動機 ......................................................................................... 1
第二章 原理介紹......................................................................................................... 4
2-1 氮化鎵材質的介紹 ..................................................................................... 4
2-2 發光二極體的原理與介紹 ......................................................................... 5
2-3 發光二極體的發光效率 ............................................................................. 7
2-4 電流聚集效應 ............................................................................................. 8
2-5 金屬與半導體的接觸 ............................................................................. 10
第三章 元件的製作與模擬....................................................................................... 14
3-1 製程示意圖 ............................................................................................... 14
3-2 製程步驟 ................................................................................................... 16
3-3 製程儀器介紹 ........................................................................................... 20
3-4 模擬過程 ................................................................................................... 25
第四章 量測結果 ..................................................................................................... 28
4-1 設計電極幾何形狀 ................................................................................... 33
4-2 實作 LED 與模擬結果 ............................................................................. 40
第五章 結論............................................................................................................... 57
參考文獻..................................................................................................................... 58

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