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標題: 圖案化藍寶石晶體蝕刻面對氮化鎵發光 二極體特性影響之研究
Effect of Crystallography-Etched Facets of Patterned Sapphire Substrates on Performance of GaN-Based LEDs
作者: 林威廷
Lin, Wei-Ting
關鍵字: GaN
light-extraction efficiency
出版社: 精密工程學系所
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摘要: 為了降低差排密度與提升光取出率,本論文主要利用黃光微影技術配合濕蝕刻製程製作圖案化藍寶石基板。我們在光罩上設計不同大小與間距的圖案來分析藍寶石基板圖案大小與間距對於元件光強度的影響。圖案大小與間距將影響濕蝕刻後藍寶石基板總表面積,藍寶石基板表面積的增加將能增加光萃取率而濕蝕刻產生之晶體蝕刻面能降低氮化鎵磊晶膜差排密度。因此嘗試製作一種晶體蝕刻面最大化的圖案化藍寶石基板,並對其磊晶膜進行品質與特性分析。 我們得到圖案化藍寶石基板氮化鎵磊晶膜最佳rocking curve半高寬值於對稱面(002)面為283 arcsec,非對稱面(102)面為274 arcsec。在350mA電流注入下圖案化藍寶石發光二極體比一般藍寶石發光二極體光輸出功率提升約40%,光強度提升約108%。此提升除了因為缺陷密度下降使得內部量子效率提升,另一方面也因為晶體蝕刻面能有效提高其光取出效率。藉由穿透式電子顯微鏡,發現氮化鎵磊晶膜內部差排彎曲集中並形成規則性排列,這是氮化鎵磊晶膜品質改善的證明。
In this thesis, in order to decrease the threading dislocation density (TDD) and enhance the light extraction efficiency, we used the photolithography technology and wet-etching process to fabricate patterned sapphire substrates. We design the mask pattern with different size and spacing and to investigate the effect of different patterned sapphire substrate on light intensity. It was found that the mask pattern size and spacing will affect the c-plane ratio. Sapphire surface area will increase the rate of increase in light extraction. Crystallography-etched facets can reduce the dislocation density. So we try to design a kind of patterned sapphire substrate. The best full width at half maximum (FWHM) of GaN rocking curve symmetric (002) and asymmetric (102) are 283 and 274 arcsec, respectively. Under a 350mA current injection current, the output power of the stripe patterned sapphire subtrate LED is enhanced by 40% and light intensity increased about 108% as compared with that of the conventional LED. These results indicated that the decreased dislocation density could enhance the internal quantum efficiency and the Crystal lography-etched facets could improve the light extraction efficiency. By transmission electron microscopy(TEM) we found the dislocations bending and regular arrangement of the formation, which proved to improve the quality of GaN epitaxial films.
其他識別: U0005-1402201109140500
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