Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/9852
標題: InGaN-based Light Emitting Diodes with the Pattern-Nanoporous Structures through Photoelectrochemical Process
利用光輔助電化學技術製作具圖形化 奈米多孔隙結構之氮化銦鎵發光元件
作者: Chen, Kuei-Ting
陳奎廷
關鍵字: 氮化銦家發光二極體;InGaN-based ligh emitting diodes;光輔助電化學;photoeletrochemical
出版社: 材料科學與工程學系所
摘要: 
本論文中利用光輔助電化學氧化及氧化物蝕刻製程,在氮化銦鎵發光二極體磊晶片之p型氮化鎵磊晶層表面製作具圖型化奈米多孔隙結構之微米孔洞陣列(nanoporous micro-hole array, NMHA)及微米圓盤陣列(nanoporous micro-disk array, NMDA)發光二極體元件。我們利用顯微光激發螢光光譜來定義奈米孔隙結構之形成與光激發螢光波長及強度關係。在電激發光光譜量測上,NMDA-LED有較明顯之波長藍移現象,可歸因於量子井發光層經由局部壓縮應力釋放後壓電場減小與能帶變得平緩所導致。在電激發光光譜波長對直流注入電流特性曲線中,亦發現到NMDA-LED發光元件比起標準試片有較少的波長藍移量,而NMHA-LED元件則是與標準試片有著相近的波長藍移量,由此可觀察出NMDA結構具有較明顯的應力釋放現象。在元件發光強度對直流注入電流特性曲線量測中,NMHA及NMDA發光二極體在20 mA的直流注入電流下各有12.3%及20.6%的光強度提升。在元件電性量測部分,可以觀察到元件的順向操作電壓與串聯電阻會隨著元件表面奈米多孔隙結構之面積比例增加而有增大趨勢。在遠場輻射(far-field radiation)特性的量測之中,我們觀察到NMHA-LED及NMDA-LED在遠場輻射圖型上的改變,造成此兩種元件在場型上的變化,是來自於兩者在結構上的差異而使得元件產生不同光取出機制。
另一方面,在NMHA-LED及NMDA-LED之太陽能電池特性量測中,我們發現藉由將奈米多孔隙結構製作於p型氮化鎵層表面時,對於氦鎘雷射光的激發產生了極大的吸收效應,可產生額外的光激發載子於量子井中結合發光。在頻譜響應量測中,發現到p型氮化鎵表面的奈米孔洞結構對於入射光之轉換效率是遠高於多重量子井發光層的,因此在元件表面具有較大比例奈米多孔隙結構的NMDA-LED元件比起NMHA-LED元件,其頻譜響應峰值更往短波長飄移了10 nm而更接近氮化鎵材料能隙吸收。由實驗結果可以了解,利用光輔助電化學氧化及氧化物蝕刻製程所製作出的奈米孔隙結構,在發光元件與光伏元件上具有極大的應用潛力。

In this thesis, the InGaN-based light emitting diodes (LEDs) with nanoporous micro-pattern array structures have been study. The pattern-nanoporous p-type GaN:Mg surface of the InGaN-based LEDs was fabricated through a photoeletrochemical wet oxidation and oxide-removal process. The formation mechanism of nanoporous structures was also discussed. The blueshift phenomenon of the PL emission peaks were observed that the compress strain in the InGaN active layer was partial released by adding the PEC cycle times and forming the nanoporous structure. The blueshift phenomenon of the electrolumescence (EL) spectra in nanoporous micro-disk array LED structure were observed that could be caused by adding the roughened area on micro-disk array pattern than the micro-hole array pattern. At 20 mA operation current, the light output power of the nanoporous micro-hole array and micro-disk array LEDs had 12.34% and 20.6% enhancement compared with the standard LEDs, respectively. The different in far-field emission patterns were observed in these nanoporous micro-pattern array LEDs. The internal quantum efficiency and light extraction efficiency of an InGaN/GaN MQW active layer are increased by forming the nanoporous structure on p-type GaN:Mg surface. This PEC treated nanoporous structure is suitable for high-power lighting applications.
The photovoltaic effect of these nanoporous micro-pattern array devices was analyzed. The spectral response was toward short wavelength region by adding the nanoporous area on the mesa region. The LED structure with the nanoporous micro-pattern structure had the higher external quantum efficiency at the UV region that had a potential application in the InGaN-based solar cell devices.
URI: http://hdl.handle.net/11455/9852
Appears in Collections:材料科學與工程學系

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