臺灣博碩士論文加值系統

本論文是在發光二極體活性層底下的氮化鎵磊晶層中摻雜矽(Si)製作出具有奈米多孔隙結構的反射鏡之氮化鎵發光二極體元件。首先利用雷射切割技術中的表面切割方式在晶粒非發光區域製作出深度約10um的切割線，使Sapphire上方的具有摻雜矽的氮化鎵磊晶層裸露於LED晶粒側壁，也就是要進行電化學蝕刻的目標區域。接下來以電化學蝕刻製程技術對於n+-GaN doping Si磊晶層進行蝕刻，此電化學蝕刻的原理主要是利用硝酸對於磊晶層中doping Si的GaN具有蝕刻的特性，使我們有效的在氮化鎵發光二極體的活性層下方區域製作出具有高反射的奈米多孔隙結構，此結構可以有效的減少光在逃逸出LED前所受到材料吸收的光損失。
利用本論文的方法製作出具有奈米多孔隙(GaN/Air堆疊層)反射鏡的GaN LED，因奈米多孔隙位於活性層底下且具有差異較大的折射率，其原理等同於活性層底下製作出一布拉格反射鏡(DBR)，因此可得到很好的反射效果，提升更多的發光效率。
本論文是將此結構製作於綠光的氮化鎵發光二極體，研究發現具有奈米多孔隙結構的反射鏡對於LED光特性包含光激發螢光光譜(Photoluminescence；PL)、電激發螢光光譜(Electroluminescence，EL)及發光強度分布均勻性(Beam Profile)的量測結果都有明顯提升趨勢，由此可見此製程技術對於將來氮化鎵系列LED其電轉換光效率的提升具有相當大的發展潛力。

In this thesis, a gallium nitride light-emitting diode with a nano-porous structure is fabricated by epitaxy of Si-doped GaN which under the LED active layer. First, a scribe line with a depth of about 10 μm was fabricated in the non-luminous area by means of surface cutting in the technique of laser cutting,the epitaxial layer of Si-doped GaN which above sapphire is exposed on the side of the LED die,that is the electrochemical etching of the target area, etching of n+-GaN doping Si epitaxial layer by electrochemical etching process,the principle of this electrochemical etching is mainly that nitric acid is used for etching GaN doping Si in the epitaxial layer,let us successfully in the gallium nitride light-emitting diode region below the active layer to produce highly reflective nanoporous structure, This structure can effectively reduce the optical loss of light absorbed by the material before it escapes the LED.
Using the method of this paper to produce nanoporous (stacking by GaN / Air) mirrors in a GaN LED,which structure because of it is large difference in refractive index,the principle is the same as making a Bragg reflector (DBR) under the active layer, so you can get a better reflectivity and then improve the luminous intensity.
The application of green gallium nitride light emitting diodes, this study found that LED light characteristics Of the measurement, including Photoluminescence 、 Electroluminescence and Beam profile have an upward trend, In the future, this process technology can improve the development of GaN LED luminous characteristics will have great potential.

致謝 i
摘要 ii
Abstract iii
目錄 iv
圖目錄 vi
第一章 序論 1
1-1發光二極體發展概況 1
1-2 LED的應用 3
1-3 研究動機 4
第二章 原理與文獻回顧 5
2-1 LED發光原理 5
2-2 LED的光萃取效率 6
2-3 LED光萃取效率的提升方法 8
2-4 雷射處理(Laser Scribing) 16
2-5 電化學蝕刻 (Electrochemical Etching) 19
第三章 實驗步驟與方法 20
3-1 實驗樣品製備 20
3-2 雷射切割方式 21
3-3 電化學蝕刻調整 23
3-4 實驗分析與量測 25
3-4-1光學顯微鏡（Optical Microscope, OM） 25
3-4-2掃描式電子顯微鏡(Scanning Electron Microscope；SEM) 25
3-4-3光激發螢光系統(Photoluminescence；PL) 26
3-4-4電激發螢光系統(Electroluminescence，EL) 27
3-4-5發光強度分布均勻性量測系統(Beam Profile Measurement System) 28
3-4-6發散角量測系統(Radiation Pattern Measurement System) 29
第四章 實驗結果與討論 30
4-1 奈米多孔隙光特性提升失效分析 30
4-1-1異常試片的外觀確認 30
4-1-2電激發螢光光譜分析(Electroluminescence，EL) 31
4-1-3發光強度分布均勻性分析(Beam Profile) 32
4-1-4 N-PAD to N-PAD歐姆接觸量測(Ohimc contact) 33
4-1-5奈米多孔隙光特性提升失效改善驗證 33
4-1-6失效真因(Failure root cause) 36
4-2 具有奈米多孔隙的發光二極體量測 37
4-2-1試片在光學顯微鏡的表面形貌 37
4-2-2掃描式電子顯微鏡的形貌 37
4-2-3光激發螢光光譜分析(Photoluminescence；PL) 38
4-2-4電激發螢光光譜分析(Electroluminescence，EL) 40
4-2-5發光強度分布均勻性分析(Beam Profile) 41
4-2-6發散角度量測(Radiation Pattern Measurement) 42
第五章 結論與未來展望 44
5-1 結論 44
5-2 未來展望 45
參考文獻 46

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