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    题名: 圖案化藍寶石基板之濕式蝕刻;Wet etching of patterned sapphire substrates
    作者: 吳麗雲;Li-Yun Wu
    贡献者: 機械工程研究所
    日期: 2006-07-05
    上传时间: 2009-09-21 11:54:34 (UTC+8)
    出版者: 國立中央大學圖書館
    摘要: 摘要 本論文主要探討使用化學濕式蝕刻法來蝕刻藍寶石(sapphire)基板,其優點在於其製程簡單、成本低廉、且蝕刻速度快,雖然藍寶石基板具有極佳物理及化學穩定性,不易和化學溶液起反應,但是本研究已成功的蝕刻藍寶石基板,且找到最佳之化學溶液配比,不僅蝕刻速率快且表面品質佳。影響藍寶石基板的蝕刻速率有化學溶液配比、溫度、遮罩圖案方向、藍寶石基板之晶格方向等因素,本文分別探討不同參數對蝕刻速率及表面品質之影響,並且定義出蝕刻的機制。在圖案化藍寶石基板上成長氮化鎵發光二極體結構後,結果顯示,氮化鎵磊晶薄膜品質有明顯提升。在光學特性方面:使用圖案化藍寶石基板成長之氮化鎵薄膜,和沒有製作圖案化藍寶石基板比較:發光效率也提升不少,證實圖案化藍寶石基板除了幫助磊晶品質改善之外,基板上之規則圖案破壞了活性層產生之光線的全反射現象,可以有效提高LED 的發光效率。 Abstract In this study, we employed a chemical wet etching method in building the trench pattern on the sapphire substrates. Compared to dry etching, wet etching had several advantages, such as simpler process, higher etching rate and throughput, and the cost is much lower. Sapphires had excellent physical and chemical stability, and it’s hard to react with the chemical solutions. Here we had already succeeded in etching the sapphire substrates, and finding out the suitable chemical solutions and working temperature to obtain the optimal etching rate and surface quality. We also discussed the relationship between etching morphology and sapphire orientations. GaN light-emitting diodes were deposited on pattern and non-pattern sapphire substrates to reveal the thin film quality and optical performance. Experimental results show the treading dislocation density of epitaxy layer was decreased obviously. A further Photoluminescence(PL)was measured and peak intensity was found to enlarge substantially for the LED sample on the pattern sapphire. This could attribute to the reduction of dislocation density, and the multiple scattering of the emission light at the GaN/patterned sapphire interface changes the angle of propagation of the confined light.
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