臺灣博碩士論文加值系統

隨著紫外光LED需求增加，製備高品質紫外光LED也成了首要目標，然而氮化鎵的異質磊晶使的氮化鎵薄膜產生大量穿隧差排，產生非輻射電子電洞複合中心，大幅度降低磊晶品質以及發光效率。
在本篇論文中，我們使用圖案化藍寶石基板技術，並透過有機金屬化學氣相沉積磊晶出高品質的氮化鎵，我們使用拉曼頻譜分析與濕蝕刻蝕刻孔洞密度的方法，來證實圖案化藍寶石基板技術確實提高了氮化鎵的磊晶品質。實驗結果顯示，利用圖案化藍寶石基板技術，我們成功將拉曼頻譜半高寬由平片2.64 (cm-1) 降到2.31 (cm-1)，縮減了12.6%，蝕刻孔洞法亦指出缺陷密度減少了20.5%，大幅度提升了氮化鎵薄膜磊晶品質。
研究亦透過設計不同週期、比例、深度的微結構，獲得不同磊晶品質的氮化鎵薄膜，以半高寬及殘存應力建構一套完整的物理模型，我們的物理模型成功預測不同週期、比例與深度的品質變化，並可透過此預測LED磊晶之結果。

With the increasing demand for ultraviolet LEDs, the fabrication of high-quality UV LEDs has also become the primary work. However, the heteroepitaxial of GaN on sapphire substrate induces a large number of threading dislocation. These dislocations become electron-hole pair non-radiative recombination centers, which dramatically decline the quality of GaN and reduce luminous efficiency.
In this paper, we grow GaN through Metal-Organic Chemical Vapor Deposition (MOCVD) and introduce its crystal quality by introduce the patterned-sapphire substrate technology. We use Raman spectrum analysis and etch pit density method to investigate and calculate the defect density. The Raman spectrum shows a decrease of FWHM from 2.64 (cm-1) to 2.31 (cm-1), which is about 12.6% improvement, and the EPD method indicates around 20.5% reduction of defect density. The results successfully confirmed that the epitaxial quality of GaN is improved with the patterned-sapphire substrate technology.
Different periods, ratio, and depths of pattern structures have been designed to verify the trend of crystal quality, and we conclude a complete physics model for the quality prediction of GaN epitaxy.

口試委員審定書 I
致謝 II
中文摘要 III
Abstract IV
目錄 V
圖目錄 VII
表目錄 IX
第一章 緒論 1
1.1 前言 1
1.2 研究動機 2
1.3 論文架構 3
第二章 實驗理論介紹 5
2.1 藍寶石基板(Sapphire Substrate)介紹 5
2.2 氮化鎵介紹 7
2.3 拉曼量測原理 10
第三章 實驗儀器與元件製備 13
3.1 製程儀器簡介 13
3.1.1 電漿輔助化學氣相沉積鍍膜系統(PECVD) 13
3.1.2 電子束微影系統(Electron Beam Lithography) 15
3.1.3 電子束蒸鍍機 (Electron Beam Evaporator) 18
3.1.4 反應離子蝕刻 (Reaction Ion Etching) 19
3.1.5 Metal–Organic Chemical Vapor Deposition(MOCVD) 20
3.2 量測儀器簡介 23
3.2.1 Scanning Eletron Microscopy(SEM) 23
3.2.2 微拉曼光譜量測系統(μ-Raman) 24
3.3 元件設計介紹(本章節與易振楷同學合作，經指導教授同意共同撰寫) 25
3.4 樣品製備(本章節與易振楷同學合作，經指導教授同意共同撰寫) 28
3.4.1 圖案化藍寶石基板製作 28
3.4.2 365nm AlGaN base UVLED結構磊晶 36
第四章 實驗結果與分析 37
4.1 磊晶品質量測與分析 37
4.2 LED全結構品質與u-GaN物理模型之關係 51
第五章 結論 55
5.1 設計封裝365nm LED之圖案化藍寶石基板 (本章節與易振楷同學合作，經指導教授同意共同撰寫) 55
5.1.1 第一道光罩---Mesa isolation 55
5.1.2 圖案設計介紹 56
5.1.3 圖案大小與Alignment mark設計 57
5.1.4 光罩對位問題 58
5.2 總結 59
5.3 LED全結構最佳磊晶結果預測 60
參考資料 61

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