1 |
Light Extraction Enhancement of GaN Based LEDs Using Top Gratings, Patterned Sapphire Substrates, and Reflective SurfacesChavoor, Greg 01 June 2012 (has links) (PDF)
In the last 15 years, an immense amount of research has gone into developing high efficiency Gallium Nitride based light emitting diodes (LED). These devices have become increasingly popular in LED displays and solid state lighting. Due to the large difference in refractive index between GaN and Air, a significant amount of light reflects at the boundary and does not escape the device. This drawback decreases external quantum efficiency (EQE) by minimizing light extraction. Scientists and engineers continue to develop creative solutions to enhance light extraction. Some solutions include surface roughening, patterned sapphire substrates, and reflective layers.
This study proposes to increase external quantum efficiency and optimize light extraction efficiency of several LED structures using finite difference time domain analysis (FDTD). The structures under investigation include GaN based LEDs with nanoscale top gratings, patterned sapphire substrates in combination with SiO2 nanorod arrays, and reflective surfaces below and above the sapphire substrate. First, we optimize GaN based nanoscale top gratings and increase light extraction by 17.8%. Next, we simulate ITO based top gratings and enhance light extraction by 40%. Third, we optimize patterned sapphire substrate period and width and the vertical position of a SiO2 nanorod array. We achieve as high as 51.8% improvement in light extraction. Finally, we increase light extraction by 160% with the use of a silver reflection layer.
|
2 |
Herstellung von GaN-Schichten mittels Hochtemperatur-GasphasenepitaxieSchneider, Tom 03 August 2022 (has links)
Verbindungshalbleiter mit einer großen Bandlücke wie Galliumnitrid (GaN) sind aufgrund ihrer hervorragenden elektronischen Eigenschaften für die Halbleiterindustrie von großem Interesse. Die Hochtemperatur-Gasphasenepitaxie, die auf dem physikalischen Gasphasentransport von Gallium basiert, ist eine alternative Methode der Gasphasenepitaxie von GaN. Im Mittelpunkt der vorliegenden Arbeit standen die Weiterentwicklung der Methode hinsichtlich der Verringerung der Kontamination und die Reduzierung der Versetzungsdichte in den GaN-Schichten. Dazu wurde eine neue Verdampfungszelle entwickelt und die komplexen, mehrstufigen Nukleations- und Wachstumsprozesse systematisch untersucht. Insgesamt wurden zu kommerziell verfügbaren GaN-Schichten vergleichbare Defektdichten erreicht. Zusätzlich wurde die Methode zur Abscheidung auf Saphir-Substraten mit einem Durchmesser von bis zu 2 Zoll aufskaliert.
|
3 |
以專利分析之觀點探討LED製程技術對中國LED產業及市場的影響 / The impact of LED manufacturing process technology on LED industry and market in China: patent analysis perspective洪駿之, Hung, Jackson Unknown Date (has links)
在二十一世紀中, LED發光二極體更是備受期待的節能產品。過去背光源一直是LED主要應用項目,而漸漸地照明也開始採用LED產品,甚至各國已宣布將禁用白熾燈。然而,在各國政府及業者大力推廣及投入LED產業之際,目前LED產品尚未能實現市場替代效應之事實卻不容忽視。細究其可能原因,是否LED產品仍有技術功能缺陷,抑或其價格無法競爭,又者消費者對產品認知不足、終端通路尚未成熟、品牌塑造尚待建立等因素,讓消費者暫時裹足不前?
鑒於台灣在LED產業中已有完整的上中下游布局,不但是下游封裝的全球最大供應中心,近年更也逐步紮根中游晶粒產品,甚至切入上游單晶基板、磊晶產品製程。故此,本研究希冀探查現有LED產品所遭遇之困難,以功能品質及經濟價值等角度,找尋可突破市場瓶頸之關鍵因素,並針對其中可進行專利檢索及分析的較具技術性因素:LED單晶基板,以中國大陸此成長最為顯著之市場作為專利檢索及分析之核心地理區域,探討LED單晶片基板之專利發展趨勢以及研發參考目標及方向。
在進行專利檢索之前,本研究將先行剖析現有LED單晶片基板的應有功能、重點特性、4大類基板材料選擇與其最新研發優勢,包含藍寶石、碳化矽、矽、氮化鎵,以助於後續專利檢索及分析結果之觀察思考。本研究的結論與建議將分別針對不同的LED單晶片基板材料選擇,以專利分析結果對照其市場發展近況,向台灣業者提出藍寶石、碳化矽已係過度競爭、不宜進入的項目,並在最後建議台灣業者仍可持續投入研發LED矽、氮化鎵基板材料,以及額外以技術與應用創新增加其產品的市場連結度及應用產業競爭利基。 / Nowadays LED has become a future mainstream of highly expected energy-saving product. Back-lighting has been the main application for LED, such as in monitors, and furthermore lighting has grown its market size into significance. However, it should draw attention that LED products has not yet fully replace conventional lighting as expected, due to a number of possible factors, including functions, prices, consumer awareness, channeling, and/or branding.
In light of the fully established LED industry in Taiwan, including the largest downstream packaging supply source, mature middle-stream wafer production and leading upstream epitaxy and substrate manufacturing, this study aims to seek and find the patent searchable and analyzable part of the current LED obstacles in product quality and economic value perspective. As a result, single crystal substrate falls into abovementioned criteria, including four major substrate materials: sapphire, silicon carbonate, silicon, and gallium nitrite. This study further concentrates the patent search and analysis on China, the fastest growing LED market among all regions and the biggest opportunity for Taiwan players.
Before patent search, this study gives a detailed elucidation about four substrate materials on functions, important traits, different types and respective R&D updates and breakthrough, followed by interpretation of and association with patent search and analysis. At the end of this study, conclusions and suggestions are given, based on Taiwan players’ current relative strength and weakness. In sum, sapphire substrates and silicon carbonate substrate have overly competitive patent and market situation, and silicon substrates and gallium nitrite substrate may allow Taiwan players to continue and/or reinforce R&D investment. Additionally, technology and application innovation could increase product-market linkage and competitive edge in LED application industry.
|
Page generated in 0.0906 seconds