本論文主要是針對具有金屬反射鏡之電極應用於藍光發光二極體之製做與研究。首先我們測試不同金屬在不同厚度之穿透率與反射率，取得較佳之反射率條件後，將其結果應用至310μm見方之藍光發光二極體元件上，再於n型氮化鎵或氧化銦錫(Indium Tin Oxide，ITO)接觸層與鉻/金電極間鍍上鋁或銀做為金屬反射鏡，接著與傳統僅具有鉻/金電極與上述之元件做各項特性之比較，此外，本論文並對n型氮化鎵上有無ITO接觸層之元件做比較。就元件大小為310μm見方之發光二極體而言，n型氮化鎵上無ITO光輸出功率有些許提升之趨勢，但由於電性不佳故不採用其結構，而在金屬反射式電極方面，具有銀做為反射鏡材料在電性上優於鋁，製做為發光二極體後增加之光輸出功率也大於後者。將其結果應用在具有不同大小之發光二極體元件上反覆印證也獲得同樣的結論。最後並將此一結構應用在市面上已廣為被接受的圖案化藍寶石(Patterned Sapphire Substrate，PSS)基材發光二極體元件上，觀察兩種結構是否可相輔相成，得到同樣之光輸出功率增加趨勢。綜觀本研究成果可得知介於氮化鎵接觸層與鉻/金電極間金屬反射鏡確實可有效提升發光二極體之光輸出功率。

In this study, we demonstrate a GaN-based light-emitting diode (LED) with non-alloyed metal contacts onto the n+-GaN surface and transparent contact layer (indium tin oxide) to serve as the n-type electrode (cathode) and the p-type electrode pad (anode) respectively. Comparing with the conventional LEDs, which the electrode pads and/or Ohmic contacts form through conventional Cr/Au metal contacts, the non-alloyed metal contacts (Ag/Cr/Au or Al/Cr/Au) used in the present experimental blue LEDs also play the role of reflector to prevent the emitted light from absorption by the opaque electrode pads with low reflectivity (Cr/Au). With an injection current of 20mA, the enhancement in the light output power has approximately a 15 percent magnitude compared to the GaN-based LEDs without Ag or Al reflectors under the Cr/Au electrode pads. Before we observed the above-mentioned results, related fundamental studies, such as the transmittance and the reflection for Al, Ag and Cr metal film deposited on GaN epitaxial layers with different thickness, are also systemically characterized. To further realize whether the above conclusion can meet different device geometries or not, the same experiment are also perfored to GaN-based LEDs with different sizes and electrode arrangement.Since the key point of this study is based on the enhancement of light extraction by high reflective metal/semiconductor interfaces ( i.e., Ag/GaN, Ag/ITO, Al/GaN and Al/ITO interfaces), the inherent GaN/sapphire interface in GaN/sapphire-based LEDs also plays an important role for light extraction. Therefore, in this study, LEDs with and without patterned sapphire substrate are also prepared to contain the above-mentioned reflective pads. This experiment results make us know that the enhancement of output power in GaN-based LEDs with high-reflectivity metal reflector under the Cr/Au electrode pads is repeatable and independent of the device structure, size and geometry.

第一章
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第二章
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第三章
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