近年來，由於發光二極體受限於其半導體高折射率，使得其外部量子效率很不理想。因此許多研究提出各種不同方法來改善光取出效率。本論文的研究目的即為利用調製多孔陽極氧化鋁的奈米孔洞來提升發光二極體的光輸出。多孔氧化鋁的孔洞排列具有規則性或粗糙特性的兩種型態。孔洞陣列的形成是藉由自我成長的機制。製作規則的奈米孔洞模板可以應用於光子晶體的發光二極體，而利用氧化鋁多孔性可以使發光二極體的表面粗糙化進而降低臨界角增加光取出。
我們藉由設計裝置樣品的載具和拋光鋁箔片，製作出具有規則排列奈米孔洞陣列，其大小約1-5 μm。陽極氧化的載具設計成可以形成均勻的電場，而且可以避免電解液滲入內部。我們利用化學和電解拋光得到平滑的表面。此外我們採用二次氧化法來製作規則孔洞，其概念是根據在表面產生圖案輔助成長的方式。在浸泡磷酸之後孔洞的直徑大約是60 nm，間距大約是70 nm。
再者我們將多孔陽極氧化鋁薄膜應用於磷化鋁鎵銦發光二極體上，藉由改變孔洞寬化時間來調變孔洞的大小和結構。奈米孔洞的直徑從30 nm變化到60 nm，而且表面粗糙度和傳統的發光二極體1.7 nm相比增加至14-20 nm。我們可以得到最佳的光輸出改進為39 %，經由40分鐘的寬化處理形成最適當的孔洞分佈。此多孔陽極氧化鋁薄膜扮演為中介層和散射中心在空氣和半導體材料之間，導致低的臨界角損失和Fresnel損失。

Recently, the external quantum efficiency of light emitting diodes (LEDs) is poor due to the high refractive index of semiconductor. Many researches reported various methods to improve the light extraction efficiency. In this thesis, we used porous anodic alumina (PAA) nanopores with modulation for improving the light output of LEDs. The pore arrangements of porous alumina have two types: regularity and roughness. The formation of pore array bases on self-organized mechanism. Fabricating ordered nanopore template can apply for photonic crystal LEDs, and the porosity of alumina is used for rough surface of LEDs to reduce the critical angle and increase the light extraction.
We fabricated an ordered nanopore array with domain size of 1-5 μm by designing a sample holder and polishing the aluminum foils. The anodizing holder is designed for forming a uniform electric field and prevents the electrolyte from soaking. We obtained a smooth surface by both chemical & electrolytic polishing. Besides, we take the two-step anodization with pre-pattern guided concept to form the regular pore array. The diameter of pores is about 60 nm after immersing in phosphoric acid and the interpore spacing is about 70 nm.
Furthermore, we applied PAA films onto the surface of AlGaInP LEDs with modifying the pore size and the structure by changing pore-widening time. The diameter of nanopores varies form 30 nm to 60 nm and the surface roughness increases 14-20 nm comparing with 1.7 nm of conventional LED. We obtained the best improvement is 39% in light output intensity with appropriate pore distribution after 40 minutes pore-widening treatment. PAA films act as the intervening layer and scattering centers between the air and the semiconductor material results in low critical angle loss and Fresnel loss.

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