本論文主要目的是探討運用p型材料氧化鎳作為閘極氧化層，使氮化鋁鎵/氮化鎵高電子遷移率電晶體達到增強型。藉由液態旋塗氧化鎳薄膜與後退火處理，可達成高電洞濃度之薄膜，p型氧化鎳薄膜在此研究扮演抬升傳導帶高於費米能階的功用，高電洞濃度的薄膜可使空乏型的高電子遷移率電晶體變成增強型。
氧化鎳，是一個低毒性、低成本、且有極佳的化學穩定性、光學性質以及電性，被發表為一個p型半導體，為了更了解氧化鎳薄膜，表面粗糙度分析、晶向分析、X光光電子譜儀分析等將在論文中探討。其中，使用了兩種合成氧化鎳的配方，並對溶液進行微調，並比較其特性。氧化鎳之功函數、厚度以及電洞濃度會影響元件特性。其中以晶向分析最為重要，塗佈之氧化鎳薄膜在氧氣環境下高溫退火，能將晶向強度(200)與晶向(111)增加，原因為鎳空缺與氧離子增加，使電洞濃度上升，最後發現不同溫度的退火會影響晶向強度，隨著溫度增加，晶向強度增強。接著再利用X光光電子能譜儀分析，確保氧化鎳薄膜能表現出p型半導體的特性。另外，微調之溶液退火之後的表面粗糙度雖從0.515 nm 提升至4.05 nm 但依然是相當可接受的應用範圍。
之後，將此高電洞濃度氧化鎳薄膜放於氮化鋁鎵/氮化鎵高電子遷移率電晶體之閘極下方，將之與傳統元件比較，臨界電壓從-4 V偏移至-2.15 V，閘極漏電流改善了102。這個新方法只使用便宜的材料與簡單的製程便可對氮化鋁鎵/氮化鎵高電子遷移率電晶體做出往正偏移的臨界電壓，使臨界電壓偏移了1.85 V。

The main purpose of this work is to explore the use of p-type material nickel oxide as the gate oxide layer to make AlGaN/GaN high-electron mobility transistor enhanced. The p-type nickel oxide thin film that can achieve a high hole concentration by solution spin-coating and post-annealing is considered to function as lifts up the conduction band above the Fermi level. NiOx thin films with high hole concentration can change the HEMTs operation mode from depletion to enhancement mode.
Nickel oxide, a low toxicity, low cost, excellent chemical stability, optical properties and electrical properties, was published as a p-type semiconductor. In order to realize the nickel oxide film, surface roughness analysis, x-ray diffraction, x-ray photoelectron spectroscopy will be discussed in this work. Furthermore, two solution of synthetic nickel oxides were used, and the solution was fine-tuning and its characteristics were compared. The work function, thickness, and hole concentration of nickel oxide can affect characteristics of HEMTs. Furthermore, the crystal orientation analysis is the most important here. The spin coated nickel oxide thin film is annealed at high temperatures in an oxygen ambient and this can increase the orientation strength (200) and (111) of nickel oxide due to the increase of nickel vacancies and oxygen ions so increase the hole concentration. Finally annealing at different temperatures was found will affect the strength of the crystal orientation, as the temperature increases, the orientation strength increases. Then we used X-ray photoelectron spectroscopy to ensure that the nickel oxide film can exhibit p-type semiconductor characteristics. In addition, although the surface roughness after annealing was increased from 0.515 nm to 4.05 nm, it is still a quite acceptable range for application.
Afterward, this high-hole-concentration nickel oxide film was inserted under the gate of AlGaN/GaN high-electron mobility transistor. Compared with the conventional device, the threshold voltage was shifted from -4 V to -2.15 V, the gate leakage current was improved by 102. This new method used cheap materials and a simple process to make a positive shift of 1.85 V in threshold voltage of AlGaN/GaN high electron mobility transistors.

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