臺灣博碩士論文加值系統

發光二極體一般都以外部發光量的變化來探討其發光品質，本研究以光學顯微鏡搭配高倍數物鏡與移動平台，聚焦至發光二極體表面與側面觀測近場分佈，了解發光二極體磊晶品質，並透過此光學系統去探討發光二極體由主動層產生的光，在入射圖形化藍寶石基板後微結構周圍的光強度變化，藉此觀察到散射光的行徑路線，透過模擬亦驗證我們所觀察到現象，之後藉由影像合併的方式，將發光二極體各區塊拼合成完整的晶片，透過此方式得知在不同操作電流下，發光二極體內部的電流分布並不均勻，發光強度較強的區域集中在電極附近，隨著電流的上升，此現象越為明顯。接著我們對發光二極體之遠場光型變化做研究，透過模擬比較有無圖形化藍寶石基板之發光二極體，得知在遠場光型方面，兩者趨勢大致相同，主要還是以外部封裝對遠場光型影響較大。最後我們提出四種不同微結構，藉由模擬改變其不同間距、高度與半徑，觀察對光萃取效率之影響，由研究結果顯示當微結構間距越小時，有最好的光萃取效率，而當微結構深寬比達到約1:1時，有最好的光萃取效率，其中又以圓錐形34.2%最高，與無圖形化藍寶石基板的發光二極體比較，成長了約72%左右。透過本光學系統，可即時的將發光二極體之內部發光變化呈現出來，對未來設計晶片提供參考與協助。

In general, the light emitting diodes (LEDs) are discussed its luminous quality by the variation of external light of LED. We use optical microscopy in combination of high magnification objective lens and mobile platform, We could focus on the surface and lateral regions of LED to investigate the epitaxy quality. Through the optical system we would investigate the light intensitiy distribution of pattern when the light emit in the patterned sapphire substrate, and we verify this phenomenon by lighttools optical simulation software. We could merger different luminous regions of LED by the different injection current. As the different injection current, we could investigate that current spreading in the internal regions of LED was not uniform. The light intensity would stronger concentrate in the nearby electrode regions. When the injection current increased, and the phenomenon was more obvious. Then we study of far-field light pattern variation between non-patterned sapphire substrate and patterned sapphire substrate. The results showed that far-field light pattern had same profile between non patterned sapphire substrate and patterned sapphire substrate LED. Finally, we design four different shapes of patterned sapphire substrates. We changed pattern’s spacing, height and radius to investigate the effects of light extraction efficiency. As the results showed that the light extraction efficiency higher when the pattern’s spacing was closer. We found that the pattern shape which aspect ratio = 1 has the best effect to enhance the extraction efficiency. The cone shape which has the highest light extraction efficiency 34%, and the enhancement of light extraction efficiency was 72 % compare with non-patterned sapphire substrate LED. Apply this system to measure in the internal regions of LED, the truly influence of the patterned sapphire substrate effect on LED would be performed. For designing greater efficiency light-emitting diode chip provides reference and assistance in the future.

目錄
第一章 導論 1
1.1 發光二極體發展與應用 1
1.2 文獻回顧 2
1.2.1 LED發光原理 2
1.2.2 LED 發光效率 3
1.2.3 LED光萃取原理 5
1.2.4 LED效率提升方式 6
1.2.5 圖形化藍寶石基板 10
1.2.6 奈米級圖形化藍寶石基板 16
1.2.7 二次離子質譜儀分析LED結構成分 21
1.2.8 利用共焦顯微鏡觀測LED內部發光變化 23
1.3 論文架構 26
第二章 研究目的與方法 27
2.1 研究目的 27
2.2 量測設備與方法 28
2.2.1 光學顯微鏡系統 28
2.2.2 LED封裝流程與結構圖 36
2.2.3 聚焦離子束顯微鏡 40
2.2.4 二次離子質譜儀 40
2.2.5 積分球與I-V電性量測 41
2.2.6 配光曲線量測系統 44
第三章 光學模擬設計 45
3.1 蒙地卡羅追跡法 45
3.2 LED結構分析 46
3.3 LED光學模型建立 48
3.4 光學模擬參數設定 49
第四章 實驗結果與討論 53
4.1 LED各磊晶層位置 53
4.1.1 圖形化藍寶石基板與電極層 53
4.1.2 多重量子井主動層 57
4.2 LED電流分布之均勻性 60
4.3 PSS對發光分布之影響 62
4.3.1 正向觀測 62
4.3.2 側向觀測 65
4.3.3 遠場光型 73
4.4 PSS對光萃取效率之影響 76
4.4.1 不同類型的PSS 76
4.4.2 奈米級PSS LED 80
第五章 結論與未來展望 84
5.1 結論 84
5.2 未來展望 86
參考文獻 87
附錄 1.1 SIMS模擬分析 90
附錄 1.2光學模擬接收器之設定 95

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