氮化鎵屬於寬能隙(3.4 eV)材料、材料本身熱穩定性佳、能夠承受高臨界電場(3MV/cm)以及擁有高電子飽和速度(1~3×107cm/s)，適合用於高溫高壓操作之下，在高功率元件的應用具有相當之優勢，因此近年來以氮化鋁鎵/氮化鎵材料為主的電子元件受到重視，像是高電子遷移率電晶體(High electron mobility transistor)或是蕭特基二極體(Schottky barrier diode)引起熱門的討論和發展，當中以GaN-on-Silicon為主，可使用傳統CMOS產線來生產引起廣大興趣。本論文主要以氮化鋁鎵/氮化鎵蕭特基二極體於矽基板上研究為主，包含了元件之設計、製造、量測、分析。共分為兩個主題，首先為氮氣電漿處理(Nitrogen plasma treatment)和蕭特基掘入(Schottky recess)降低導通電壓，導通電壓從約0.9V降低致0.35V和使用30W、300C氮氣電漿對元件進行表面處理，漏電流從10-5A/mm降低至10-7A/mm，下降了大約2~3個數量級，有效地改善漏電流，減少表面氮空缺(Nitrogen vacancy)等相關缺陷，處理過後的元件片電阻下降約50Ω/□，也相對有較小的導通電阻，較大的順向電流和崩潰電壓超過1100V。
另個主題為雙陽極蕭特基金屬，利用低功函數的鈦金屬降低二極體的導通電壓，而高功函數的鎳作用為抑制漏電流，利用此結構有效地導通電壓約從1.2V降低0.8V上下，但會得到較大的漏電流約10-5A/mm，與傳統單一鎳金屬陽極相比大了約2個數量級，由於等效的蕭特基能障(Schottky barrier height)較小，因此鈦金屬長度比例越大，漏電流越大，導通電壓越小，而鎳金屬長度比例越大，較能夠抑制漏電流。

The properties of gallium nitride are suitable for operation under high temperature and high voltage, mainly because of the wide bandgap(3.4eV), good thermal stability, high critical electric field(3.4MV/cm) ,and high electron saturation velocity(2×107cm/s) of the material.
These advantages make gallium nitride excellent for the applications of high frequency and high power devices. The gallium nitride based device such as high electron mobility transistor (HEMT) and Schottky barrier diode (SBD) have been widely discussed and developed in recent years. Especially, the GaN-on-Silicon devices with the compatibility of CMOS process attract significant attention. This thesis presents the study of AlGaN/GaN Schottky barrier diodes on the silicon substrate, involving device design, manufacturing, measurement and, analysis.
There are two main topics included in this thesis. Frist, the AlGaN/GaN SBDs with nitrogen plasma treatment and Schottky recess is discussed. The turn-on voltage can be decreased from 0.9 V to 0.35 V, and the leakage current decreased from 10-5A/mm to 107A/mm by using nitrogen plasma treatment with 30W at 300C. The proposed method effectively improves the leakage current and reduces the surface nitrogen vacancy and other related defects. After treatment, the device sheet resistance decreases by about 50Ω/□ with a relatively small on-resistance. A large forward current and breakdown voltage over 1100V can be achieved.
Another topic is the SBDs with a dual Schottky metal anode. The use of a low work function -of titanium can reduce the turn-on voltage of the diode. On the other hand, the nickel as a high work function can suppress the leakage current. This dual-metal structure effectively reduces the turn-on voltage from about 1.2 V to 0.8 V. But the devices suffer an increased leakage current by about two orders to be about 10-5A/mm, compared with the traditional single nickel anode devices, due to the smaller equivalent Schottky barrier height. Therefore, the larger ratio of Ti/Ni of the anode results in larger leakage current and smaller VON. In contrast, with a smaller ratio of Ti/Ni, the leakage current can be suppressed.
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