利用表面粗化與鏡面基板貼合技術改善發光二極體外部量子效率之研究

高亮度發光二極體，已廣泛的運用在通訊、照明、交通、戶外看板等。磷化鋁鎵銦發光二極體，擁有高的發光效率，發光波長範圍可由黃光至紅光，並且需要磊晶成長於晶格匹配的砷化鎵基板上，但是砷化鎵基板會吸收磷化鋁鎵銦所發出的可見光且其熱傳導性較矽為差，因此限制了在高電流的發光效率。本論文研究目的是利用金和金鈹薄膜形成鏡面反射基板，其功能可以作為黏著層、反射鏡面及形成半導體之歐姆接觸層，而基板選用散熱特性良好的矽晶片來取代傳統發光二極體砷化鎵基板，以解決元件本身存在的散熱問題。並經由實驗結果得到鏡面反射基板與磷化鋁鎵銦發光二極體的最佳化黏貼製程可於溫度350℃完成。本論文之另一重點是針對發光二極體表面結構，使用化學溶液將表面蝕刻成一粗糙面，讓發光二極體產生無規則的光，以不同的射出角在多種接觸面上將光散射出去，於實驗中增加發光效率達34﹪。由於晶片黏貼發光二極體矽基板的散熱特性較原始的砷化鎵基板為佳，因此對於未來朝向高亮度、高功率與大面積的發展趨勢，以具有良好鏡面反射基板的晶片黏貼型發光二極體將更具發展潛力。

關鍵字

鏡面反射基板；發光二極體；磷化鋁鎵銦；晶片黏貼

並列摘要

High-efficiency light-emitting diodes (LEDs) are desired for many applications such as communication, illumination, traffic, and outdoor displays. It is well known that the AlGaInP LED lattice-matched GaAs substrates have the highest luminous efficiency in the yellow-to-red spectral region. However, the absorbing GaAs substrate significantly limits the light extracting performance. The inferior thermal conductivity (GaAs versus Si) also yields the joule-heating problem, which limits the luminous efficiency at high injection currents. In this thesis, wafer coated with an Au/AuBe reflector was fused to an AlGaInP LED epilayers grown on GaAs. After the wafer bonding process, the GaAs substrate was chemically removed. The metallic interlayer can be not only as an adhesive layer, but also as the reflective mirror and ohmic contact layer. The Si substrate provides a good heat sink. The performance and reliability of wafer-bonded AlGaInP /mirror/ Si light-emitting diodes have been recognized. The fusion temperature for the wafer-bonded AlGaInP LEDs was optimized at 350aC. To roughen the AlGaInP LED surface we applied wet etching method. In the roughened surface the dynamic of light rays became chaotic. The optical phase-space distribution became random, and allowed more lights to escape from the semiconductor. We have demonstrated that there was additional 34﹪improvement in the efficiency of GaAs LED by employing the above method. The better thermal conductivity of wafer-bonded AlGaInP LED with Si substrate compared that with GaAs substrate will make it possible a high potential in high-brightness, high-power and large-area applications of the wafer-bonded AlGaInP epilayers with mirror substrate.

並列關鍵字

LED ； AlGaInP ； mirror substrates ； wafer bonding

參考文獻

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[9] F.A. Kish et al. Electron. Lett. 30 1970 (1994)

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利用表面粗化與鏡面基板貼合技術改善發光二極體外部量子效率之研究

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