本論文的研究主題是藉由次微米網狀粗化發光二極體(light emitting diodes, LEDs)表面，提升其光輸出效率。在研究中，首先利用時域有限差分法(Finite-Difference Time-Domain；FDTD)模擬LEDs表面粗化對於其光萃取效率的影響，在製程部分則是採取微米球單層鋪排技術，提出兩種粗化製程：一種是溶膠-凝膠材料製程，另一種為微米球曝光顯影製程。實驗結果顯示，鋪排直徑1.5?m單層聚苯乙烯(polystyrene, PS)微米球，應用溶膠-凝膠材料製程，可將LEDs表面粗化成具有次微米級蜂巢狀結構。輸入順向電流為20mA時，未經粗化LEDs之順向電壓為3.22V，光輸出能量2.1W，結構深度為50nm與100nm具蜂巢狀表面LEDs順向電壓(forward Voltage, Vf)分別為3.32V與3.35V，相較於未經粗化之LEDs光輸出能量則分別提升19%與33%。同樣利用直徑1.5?m PS微米球，實施微米球曝光顯影製程則可在LEDs表面獲得具有次微米級空氣柱圖案樣式，此樣式達成本研究提出之光萃取效率模型之模擬設計。20mA電流注入下，當空氣柱結構深度為50nm、100nm和150nm，相較於未粗化LEDs其電性幾乎不受影響，光輸出能量則各提升9%、27%和45%，此結果與模擬結果趨勢相符，未來或可作為提升LEDs亮度之應用。The subject of this thesis is to promote the output power of light emitting diodes (LEDs) by roughening the surfaces of LEDs with the sub-micrometer netlike structures. Firstly, we simulated the effects for light extraction efficiency of LEDs with different roughened structure by Finite-Difference Time-Domain (FDTD) method. In experiments, we proposed two methods to rough the surface of LEDs by using the monolayer microspheres array technique: one is the sol-gel process, and the other one is the microsphere photolithography process. The polystyrene microspheres with diameter of 1.5?m were applied in this study. As the experimental results show, in sol-gel process, we made the honeycomb structures on the surface of LEDs. The forward Voltage (Vf) of conventional LEDs, which without roughened surface, was 3.22V and output power 2.1mW under the current of 20mA. The Vf of honeycomb structured LEDs with roughened depths of 50nm and 100nm were 3.32V and 3.35V, and the output powers compared with the conventional LEDs were promoted by 19% and 33%, respectively. In microsphere photolithography process, we could obtain the sub-micrometer air-hole pillars structures on the surface of LEDs after dry etching. Meanwhile, the air-hole pillars structures also achieved the design of the model of simulation for light extraction efficiency of LEDs. As injecting of 20mA current, the electrical property of LEDs with air-hole pillars structures were almost the same compared with the conventional LEDs. The output power of LEDs with different etching depths of 50nm、100nm and 150nm were enhanced by 9%、27% and 45% as compared with the conventional LEDs, respectively. The experimental results are consistent with the tendency of the simulation. This novel technique could be applied on industry for promoting the output power of LEDs in the future.
