次微米光柵結構於發光二極體表面之研究;A study of light-emitting diodes featuring submicron gratings

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/7011

Title:	次微米光柵結構於發光二極體表面之研究;A study of light-emitting diodes featuring submicron gratings
Authors:	曾少澤;Shao-Ze Tseng
Contributors:	光電科學研究所
Keywords:	發光二極體;光柵;LEDs;gratings
Date:	2009-07-01
Issue Date:	2009-09-22 10:34:45 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本論文研究使用雷射雙光束干涉微影法製作次微米光柵結構於發光二極體(Light Emitting Diodes，LEDs)表面，目的為改善光萃取效率，並且對於LEDs的光型調制、光場分布與發光極化率作探討，文中使用的模擬分析法為有限時域差分法(Finite Difference Time Domain，FDTD)，模擬結果顯示次微米光柵結構週期為1?m且深度為250nm時可以提升出光強度達88%。在實驗製程上，我們利用干涉曝光微影技術將干涉條紋轉印至發光二極體元件上的光阻層，再利用感應耦合電漿蝕刻系統 (Inductively coupled plasma，ICP)蝕刻轉印至發光元件表面。因此我們可得到不同尺寸的次微米光柵，藉以探討結構參數變異對於光萃取效率以及光型調制的影響。經由模擬運算及角度解析光激發螢光(Angle-Resolved photoluminescence，ARPL) 量測結果的比較，我們發現次微米光柵可以破壞氮化鎵結構內的光波導模態(waveguide mode)，使結構內部的光經由次微米光柵萃取出來，當次微米光柵週期小於1?m且蝕刻深度為200nm時，其光萃取效率能夠有效的提高，其中效率最高為週期=900nm的結構參數，其出光增強率可達到74%。由ARPL量測光型分佈可以得到未做結構之LED的0o至正負30o其出光強度會有15%的衰減；但是當週期為900nm時，其0o至正負30o的出光強度只有10%的衰減；週期為800nm和1?m時則有13%的衰減，這個結果可證明次微米光柵結構有助於提升發光二極體的正面出光均勻度。而固定0o與30o的收光角度所量測的極化率結果，發現具光柵結構之LEDs其極化率在0o及30o時分別為14.3%及25.4%；然而未做結構之LED的極化率在0o及30o時分別為1.8%及1.7% 。因此具光柵結構之LEDs其極化現象更為明顯。In this thesis, we use the two beam interference lithograph to fabricate sub-micron grating structures on the surface of GaN-based light-emitting diodes (LEDs) for improving the light extraction efficiency. We simulate the light extraction efficiency and the field distribution of the flat and the sub-micron grating LEDs by the finite-difference time-domain method. There is an 88% improvement on light extraction efficiency of the LED with the grating period of 1?m. We fabricate the sample and use the angle-resolved photoluminescence (ARPL) and angle-resolved electroluminescence (AREL) to measure the field distribution and light extraction efficiency. The output intensity of the LEDs with sub-micron gratings is significantly enhanced by 74%, compared with that without structure. According to the ARPL results, the LED with sub-micron grating structures will improve the uniformity of field distribution and the polarization ratio of extracted light.
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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