本論文之主要目的是探討運用p型氧化鎳薄膜使氮化鋁鎵/氮化鎵高電子遷移率電晶體來達到增強型。藉由濺鍍p型氧化鎳薄膜與後退火處理，可達到高電洞濃度之氧化鎳薄膜，p型氧化鎳在此篇論文中扮演抬升傳導帶高於費米能階的功用，高電洞濃度氧化鎳薄膜可使空乏式高電子遷移率電晶體變成增強式。
氧化鎳是一個低成本、低毒性、環境友善的材料，被發表為一個p型半導體，為了更了解氧化鎳薄膜(一)表面粗糙度(二)霍爾量測電洞濃度的變化(三)晶向分析(四)化學組成(五)鎳缺陷含量(六)高濃度氧化鎳模型，將會在此篇中進行探討。其中，濺鍍於氧氣電漿中之氧化鎳薄膜之電洞濃度為2.1×1017 cm-3高於氬氣電漿之電洞濃度為6.5×1016 cm-3，原因為氧化鎳晶向從(200)改變成(111)，所以鎳空缺增加使電洞濃度增加; 另外，在氧氣環境高溫退火後氧化鎳濃度更加升高至1.3×1018 cm-3歸因於氧化鎳(111)之晶向更強，也就是非化學劑量組成增加，且部分二價鎳離子轉換成三價，所以鎳空缺增加造成電洞濃度提升; 另外通氧退火之後的厚度並沒有改變而表面粗糙度雖從1.93 nm提升至 4.11 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場效電晶體之閘極下方，直流部分臨界電壓3.33V也就是從空乏型變成增強型電晶體，另外，電流開關率變成107， 順偏閘極崩潰電壓也從3.5 V 提升至 10 V，逆偏閘極崩潰電壓也從-78 V 提升至 -198 V; 相較於傳統元件，源極漏電流改善103且閘極漏電流改善105; 此外，臨界電壓的偏移遲滯沒有明顯的改變， 輸出特性曲線中的小訊號與直流訊號差異不大也就是電流倒塌效應不明顯; 在不同波寬的小訊號量測時電流下降效應也不明顯，所以波寬對電流下降影響不高; 這個新方法只使用便宜的材料與簡單的製程便可對氮化鎵高電子遷移率場效電晶體做出正的值的臨界電壓，有著低漏電流、改善電流倒塌效應、提高閘極崩潰電壓、降低臨界電壓遲滯曲線，相較於其他製作增強型的方法比起來有效降低元件之生產時間與成本，所以有商用化的潛力

The main purpose of this work is to fabricate the enhancement mode gallium nitride-based high electron mobility transistor (HEMT) by high hole concentration nickel oxide (NiOx) thin film. This special thin film is made from sputtering and post-annealing nickel oxide. The high hole concentration p-NiOx plays an important role on lifting up the conduction band of two dimension electron gas higher than Femi level. Therefore, the enhancement mode GaN-based HEMT is successfully completed.
Nickel oxide, a low-cost, low toxicity and environment friendly material, was proposed as a p-type semiconductor. To further understand the mechanism of p-type nickel oxide thin film, this work discusses a lot of characteristic including roughness, hole concentration, lattice, chemical composition, nickel vacancies, and p-NiOx model. In particular, sputtering p-NiOx in oxygen ambiance gets the hole concentration of 2.1×1017 cm-3 higher than that in Ar ambiance of 6.5×1016 cm-3. This increase resulted from the orientation of (200) to (111) and the nickel vacancies increased. After annealing in oxygen ambiance, the hole concentration gets to 1.8×1018 cm-3. This increase resulted from the orientation of NiOx (111) stronger and the Ni+2 ions became Ni+3 ions. Thus, the nickel vacancies get more than before. Besides, the thickness of NiOx, after annealing in oxygen ambiance, has no change and roughness is from 1.93 nm to 4.11 nm. Although the roughness slightly increases, it is still acceptable to apply in semiconductor devices.
The normally off AlGaN/GaN HEMT is fabricated only through p-NiOx. Vth completely shifted 3.33 V from the conventional normally on to the normally off HEMT with post-annealed p-NiOx capping layer. The on/off current ratio becomes 107. The forward and reverse gate breakdown enhance from 3.5 V to 10 V and -78 V to -198 V, respectively. The leakage currents of drain and gate decrease by three and five orders, respectively. The threshold voltage hysteresis has no significant change. The pulse measurement shows that the current collapse effect is not obviously high. With different pulse width, the current reduction only slightly decreases. This new way barely uses low-cost material and simple processes to get a positive threshold voltage for AlGaN/GaN based HEMT with lower leakage current, improvement of current collapse, higher gate breakdown voltage, and lower hysteresis of threshold voltage. Hence, it is regarded as a superior potential method to become commercially available in the future work.

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