氮化鎵材料系統被廣泛的應用於高功率發光二極體。其中很重要的一部分在於透明導電層的製作。ITO (Indium-tin-oxide)是廣泛被使用的材料之一，應用於氮化鎵系統的材料之中，卻出現了嚴重的問題，P型氮化鎵的功函數為7.5eV，ITO的功函數約為4.8eV，導致產生了蕭特基現象，使得元件本身的啟動電壓居高不下；另一個迫切需要解決的問題則是元件總電阻難以降低，高電阻所造成的問題，會使得高功率的元件產生熱損耗，導致效率降低。工業界已解決此問題但不會公開，學術界還需自行研發。
我們嘗試不同製程，利用傳輸線元件做電特性量測，將ITO於高溫退火製程中所通入的氣體由N2改變為CDA(Clean dry air)，並在ITO與P型氮化鎵中加入了氧化鎳接合層，以降低ITO與P型氮化鎵的接觸電阻以及啟動電壓，並且利用不同的方式鍍製ITO，以降低啟動電壓。
利用傳輸線實驗的結果，我們將元件的製程進行改良，製作出來的發光二極體的啟動電壓由原來的5.5V降低至2.6V，總電阻由40Ω降低至10.4Ω。

GaN material system is used for high power light emitting diodes (LED). One of the most important processes is the fabrication of a transparent conducting layer (TCL). Indium-tin-oxide (ITO) is a generally used material for TCL, however, ITO and p-type GaN have quite different work functions: 4.8eV and 7.5eV respectively. If we use ITO directly on p-type GaN, it would result in Schottky contact, leading to high turn-on voltage. In addition, to reduce the series resistance is an urgent issue, because high series resistance in high power device causes high waste heat and low power efficiency. LED manufacturers have found their solutions internally. We need to develop our own process.

In this research, we carried out different ITO processes, and used transmission line model to characterize the electrical properties of fabricated devices. The experiments include: change annealing gas from N2 to CDA (Clean dry air), add NiO layer between ITO and p type GaN, and deposit ITO layer by different means.

In result, we reduce the series resistance from 40Ω to 10.4Ω, and the turn-on voltage from 5.5V to 2.6V.

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