表面電極設計與壓印微結構對發光二極體效率之影響

The Influences of Electrode Pattern and Imprinted Microstructure on the Efficiency of Light-Emitting Diodes

陳智有(Chih-Yeeu Chen)

指導教授 ： 李有璋

中原大學/工學院/機械工程研究所/碩士(2011年)

https://doi.org/10.6840/cycu201100882

摘要

摘要
本論文的研究方向主要有兩大主題。首先是製作U型電極，使氮化鎵發光二極體縮短P型電極跟N型電極的距離，讓電流擴散距離減短，而降低串聯電阻。本論文製作出30 μm及50 μm寬度的U型電極，之後在U型電極上製作出3 μm或5 μm圓洞，使被電極遮住的光，經由圓洞結構被釋放出來；結果顯示在高操作電流下，可以減低局部電流密度過高的問題，減少發光二極體的熱效應，使得製作出30 μm U型電極及直徑5 μm圓洞圖案LED，最強的發光功率為48.09 mW，明顯高於傳統LED的43.78 mW。
壓印微結構方面，先使用濕蝕刻的方式製作出倒金字塔的矽模具，再利用聚二甲基矽氧烷(PDMS)複製出軟性的子模具，以滾輪壓印的方式製作不同折射率材料PMMA(n=1.5)、D1 (n=1.7)、A54 (n=1.9)的倒金字塔結構於LED透明導電膜。從光電特性量測結果顯示，製作結構在ITO上並不會對電特性造成影響，但微結構卻可以破壞發光二極體內部的全內反射，有利於光被萃取到自由空間當中。折射率越高的微結構，對於光學提昇效率越佳，這其中以材料A54製作的50%提升效率最佳。而本論文也利用光線追跡方式模擬不同折射率結構對發光二極體光學效率之影響，模擬結果顯示與實驗結果趨勢一致。

關鍵字

發光效率 ； 電流擴散 ； 發光二極體

並列摘要

Abstract
This thesis has two main research topics. The first is the new U-shaped p-type electrode of gallium nitride light-emitting diodes (GaN LED) to reduce the current spreading distance of p- and n-type electrodes. The width of U-shaped electrode are 30 μm and 50 μm respectively, meanwhile, hole array with 3 μm or 5 μm diameter were fabricated onto electrodes to release the light under electrode to free space. The maximum output power are 48.09 mW and 43.78 mW for the LED of U-shaped electrode with width of 30 μm and diameter of 5μm and conventional LED respectively. The result showed new electrode design reduces the thermal effect due to current crowding is alleviated.
The second topic of this thesis is to fabricate inverted pyramid microstructure withdifferent refractive index (n=1.5 for PMMA, 1.7 for D1 and 1.9 for A54)onto the ITO of LED by roller imprinting lithography. This study showed that LED with microstructure made of A54 reached 50% optical improvement compared to the conventional LED. The optical simulation by ray tracing method was also used to analyze the microstructure with different refractive index to the output power enhancement, and the simulation results have the same trend of experiments.

並列關鍵字

enhance efficiency ； current spreading ； light-emitting diodes

參考文獻

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