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系統識別號 U0026-1207201014472900
論文名稱(中文) 以蝕刻製程技術對發光二極體輸出特性之改善
論文名稱(英文) Study on Light-Output Enhancement of Light Emitting Diodes by Etching process technology
校院名稱 成功大學
系所名稱(中) 微電子工程研究所碩博士班
系所名稱(英) Institute of Microelectronics
學年度 98
學期 2
出版年 99
研究生(中文) 洪玥煜
研究生(英文) Yueh-Yu Hung
學號 q1697406
學位類別 碩士
語文別 中文
論文頁數 111頁
口試委員 指導教授-洪茂峰
口試委員-王永和
口試委員-王水進
口試委員-洪振益
口試委員-李茂順
中文關鍵字 發光二極體  表面粗化  電流阻擋層 
英文關鍵字 LED  surface texture  current blocking layer 
學科別分類
中文摘要   為達到提升發光二極體發光效率的目的,本論文主要分成兩部分,第一部分首先在發光二極體發光面沉積氧化鋅鋁(AZO)薄膜以達到折射率匹配,並採用濕蝕刻方式在AZO薄膜上製作表面粗糙化結構,來增加光散射效果,具有AZO蝕刻薄膜之LED其順向電壓僅有些微上升(~0.05V),在LED正向及側向45°角發光強度皆提升了117.43% ~119.79%。第二部分使用電漿處理p-GaN表面來製作電流阻障層並經由XPS及I-V量測分析得知,處理過程中所產生的氮空缺對p-GaN進行電洞濃度的補償以及鎵懸浮鍵與氧鍵結,導致電漿處理區域產生較高位能障與高串聯電阻以達成電流阻障的目的。由於電極下方p-GaN 區域阻值升高,使得電極下方電流無法循原先路徑流向n電極,進而降低發光區結合之光子被金屬電極所吸收,而使輸出光功率提升了12%。
英文摘要 In this thesis, we use two methods of fabrication-process to improve light-output of Light emitting diodes. The first part is to fabricate a surface-textured AlGaInP light-emitting diodes coated with transparent AZO thin film which is produced by wet etching treatment with hydrochloric acid. At 20 mA, the light output power of the AlGaInP LED coated with surface-textured AZO thin film is enhanced by ~117.43% compared with the conventional LED. The enhanced light output power is attributed to the improved extraction efficiency resulting from an overall decrease in the total internal reflection due to the AZO thin film and increased surface roughness that causes angular randomization of the photons.
The second part is to fabricate a selective high barrier region (SHBR) with inductively coupled plasma (ICP) etching that induces an increase of series resistance in p-type GaN. The plasma exposed area revealed higher resistivity in conjunction with an increased barrier height. We attribute this phenomenon to a combination of two mechanisms, one of which is the nitrogen vacancies, acting as donors for electrons were produced at the etched surface, resulting in a shift of the Fermi level moves away from the valence band maximum edge. The second mechanism is the ICP-induced Ga dangling bonds, which would adsorb oxygen from the ambient. Those leads to the rised in contact resistivity through the increase of the Schottky barrier for the conduction of electrons. Thus , the current blocking layer is simply developed below the p-pad electrode of the GaN-based light-emitting diodes (LEDs). The light-output power for the LED chip with a SHBR is significantly increased by 12% as compared with the conventional LED chip. The enhancement in the light-output power can be explained for the additional current injection into the effective active layer area of the LED by the SHBR structure and a reduction in optical absorption under the p-pad electrode.
論文目次 第一章 緒論 1
1-1 研究背景 1
1-2 研究動機 3
第二章 理論基礎與文獻回顧 5
2-1 發光二極體基本原理 5
2-2 LED發光效率與表面粗化 6
2-2-1 LED發光效率 7
2-2-2 Fresnel反射 8
2-2-3 司乃耳定律(Snell’s Law)與表面粗化 10
2-3 氧化鋅透明導電膜特性 13
2-3-1 氧化鋅薄膜的電性 13
2-3-2 氧化鋅薄膜光學特性 14
2-3-3 氧化鋅鋁(AZO)薄膜之特性 16
2-4 GaN-LED 水平結構電流分佈理論 17
2-5 以ICP蝕刻p-GaN表面作為電流阻障層(CBL) 20
2-5-1 感應耦合電漿蝕刻(ICP)基本原理 21
2-5-2 感應耦合電漿蝕刻(ICP)處理與p-GaN材料反應機制 23
2-6 傳輸線模型(Transmission-line-model;TLM)理論[41-42] 24
第三章 實驗方法與步驟 38
3-1 實驗架構 38
3-2 基本製程實驗 39
3-2-1 濕式蝕刻 39
3-2-2 反應式離子蝕刻[46,48-50] 40
3-2-3 濺鍍製程 42
3-2-4 微影製程 43
3-2-5 蒸鍍製程 44
3-2-6 退火 44
3-3 氧化鋅鋁(AZO)表面粗化製作實驗步驟 45
3-3-1基板清洗步驟 45
3-3-2 氧化鋅鋁(AZO)薄膜濺鍍製程 46
3-3-3 氧化鋅鋁(AZO)薄膜粗化實驗流程 46
3-4 氧化鋅鋁(AZO)表面粗化發光二極體製備實驗步驟 47
3-4-1 AlGaInP-LED晶圓的準備 47
3-4-2 晶片清洗[53] 47
3-4-3 氧化鋅鋁(AZO)薄膜之成長 48
3-4-4 氧化鋅鋁(AZO)薄膜粗化實驗流程 48
3-4-5 定義電極區 49
3-4-6 n型與P型電極的沉積 49
3-5 具選擇性高能障區發光二極體製備實驗步驟 50
3-5-1 GaN-based LED晶圓的準備 50
3-5-2 晶片清洗[53] 50
3-5-3 利用ICP處理製作選擇性高能障區 51
3-5-4 定義高台(Mesa)圖型 52
3-5-5 製作透明導電層(TCL)及p-GaN歐姆接觸之建立 53
3-5-6 蒸鍍金屬接墊電極 54
3-6量測分析 55
3-6-1 表面形貌分析 55
3-6-1-1 掃描式電子顯微鏡(Scanning electron microscope, SEM) 55
3-6-1-2 原子力顯微鏡(Atomic force microscopy, AFM) 55
3-6-2 紫外光-可見光光譜儀(Ultraviolet Visible Spectrometer, UV-Vis) 56
3-6-3 X光光電子能譜儀 (X-ray photoelectron spectroscopy, XPS)[55] 56
3-6-4 發光二極體光電特性分析 58
第四章 結果與討論 70
4-1 氧化鋅鋁蝕刻薄膜分析 70
4-1-1表面形貌分析 71
4-1-1-1氧化鋅鋁薄膜分析 71
4-1-1-2蝕刻時間對氧化鋅鋁蝕刻薄膜之影響 71
4-1-1-3 蝕刻濃度對氧化鋅鋁蝕刻薄膜之影響 72
4-1-2 光學性質分析 73
4-1-2-1 蝕刻時間對氧化鋅鋁蝕刻薄膜之影響 73
4-1-2-2 蝕刻濃度對氧化鋅鋁蝕刻薄膜之影響 74
4-2 氧化鋅鋁(AZO)表面粗化發光二極體分析 74
4-2-1氧化鋅鋁(AZO)表面粗化對發光二極體電性影響 75
4-2-2氧化鋅鋁(AZO)表面粗化對發光二極體光性影響 77
4-2-3氧化鋅鋁(AZO)表面粗化對LED遠場發光圖形影響 78
4-3電漿處理之氮化鎵表面特性分析 80
4-3-1以電流-電壓曲線比較電漿處理之氮化鎵表面不同阻值變化 80
4-3-2 電漿處理前後之氮化鎵表面X光電子能譜分析 81
4-3-3 電漿處理前後之二維光強度影像 82
4-4 具選擇性高能障區發光二極體分析 82
4-4-1發光二極體電性分析 82
4-4-2發光二極體光性分析 83
第五章 結論 103
參考文獻 105
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