摘要
自1995年10月日亞化學公司(Nichia)宣佈成功研製2.5燭光(cd) 450nm藍光之氮化鎵銦(InGaN)發光二極體(LED)，開始在全球光電產業造成巨大震撼，學界及業界都積極投入做研究探索。固態照明光源之發展，其中近紫外光發光二極體（near ultra-violet LED）搭配R、G、B三色螢光粉，因具有光譜涵蓋範圍廣及較高之演色性特點，因此有取代傳統以藍光LED激發黃色螢光粉的趨勢。
另一方面由於紫外光發光二極體發光效率差，我們以網格(Mesh)狀電極取代原有的透明電極，減少透明電極的光吸收，增加光萃取率，藉此提高元件之外部量子效率、光輸出功率、降低操作電壓並改善其電流分布，得到較佳之熱穩定性等特性。本論文之探討方向分為P-GaN contact與N-GaN contact之特徵電阻電性研究，將最佳化之結果應用於發光二極體元件製程，分別就其電特性與光特性研究。在P-GaN contact方面，以Ni/Au、ITO與Pd/Au為接觸電極，量測其歐姆接觸，並得到最佳特徵接觸電阻(Specific Contact Resistance, ρc)值分別為 、 及 。在N-GaN Contact方面，以Cr/Pd/Au作為接觸電極，得到最佳化ρc為 。
在紫外光二極體研究方面，以傳統Ni/Au、ITO及Mesh ITO做為透明電極，在20 mA的光輸出分別為4.09 mW、7. 54mW及9.02 mW。由結果可知，以Mesh LED製程應用於GaN LED可有效改善光電特性，使得光輸出增加、電流分佈更均勻，可加以應用於大尺寸晶粒LED。

Abstract
Since Nichia announced their success in developing 2.5 cd blue (405nm) InGaN LED in October of 1995. This begins to cause enormous shock to the global photoelectric industry. Both the academia and industry are then actively involved in studying and developing this new technology. In the development of solid state lighting, near ultra-violet LED pump Red, Green and Blue phosphors that has the characteristic of wide optical spectrum range and higher color rendering. Therefore, the method of using blue LED to pump yellow phosphor will be replaced.
Due to the low internal efficiency of UV LED, we use mesh contact layer to replace the transparent contact layer in order to reduce the absorption of transparent contact layer and increase light extraction efficiency. This method can also increase the external quantum efficiency and output power, reduce the voltage of operation, improve current distribution. It could be to obtain good thermal stability and so on. In this paper, we fabricate the low resistivity of P-type contact and N-type contact. We apply the optimization to the chip process of LED. Optical and electrical properties of fabricated LEDs will also be discussed.
In the P-GaN contact, we use Ni/Au, ITO and Pd/Au as ohmic contact and measure the specific contact resistance. The specific contact resistance are , and for Ni/Au, ITO and Pd/Au, respectively. In the N-GaN contact, we use Cr/Pd/Au as ohmic contact and the specific contact resistance is . In the research of UV LED, we use traditional Ni/Au, ITO and mesh ITO structure as the transparent contact layer (TCL). Under 20 mA forward current injection, it was found that LED output power were 4.09 mW, 7.54 mW and 9.02 mW for Ni/Au TCL LED, ITO TCL LED and mesh ITO TCL LED, respectively. Based on this result, we found that GaN LED with Mesh TCL which can increase output power and better current spreading. Due to these characteristics, the mesh TCL structure could be applied to the big chip size LED.

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