本研究共分為兩部分，第一步分為使用原子層沉積系統(Atomic Layer Deposition)分別沉積單層20奈米二氧化鉿薄膜與氧化鋁薄膜，並以氧化鉿為基底，摻雜氧化鋁去做元素比例調變，藉由調變二氧化鉿(m)/氧化鋁(n)之ALD cycle數，可得到不同鋁含量之HfxAl1-xO薄膜。當m/n比例為(1/1)、(3/1)、(5/1)時，可得到分別為Hf0.36Al0.64O、Hf0.63Al0.37O與Hf0.79Al0.21O之三元化合物薄膜。由原子力顯微鏡量測結果顯示，摻雜氧化鋁進氧化鉿中可改善表面粗糙度，雖介電常數會隨鋁成分提高而有所降低，但Hf0.63Al0.37O之介電常數仍保有約19。而相較於純二氧化鉿薄膜，鋁摻雜可將抗結晶溫度由400度提升至800度，使其具有更佳之熱穩定性。而為了瞭解退火後對材料之影響，300度氮氣中退火5分鐘之材料被研製，並使用XPS分析，可得氧空缺由原先的14.9%下降至8.6%，鉿鋁元素與氧則有更好的鍵結。鋁含量過高之HfxAl1-xO薄膜，反而因鉿原子與鋁原子間之大小差異，在薄膜成長時產生懸浮鍵(dangling bond)，進而形成漏電路徑，故後續之實驗將採用(3/1)之HfAlO作為閘極介電層。第二部分為將上述之薄膜應用於AlGaN/GaN高電子移動率電晶體之閘極介電層，以元件電性而言，最佳比例之薄膜為Al2O3/Hf0.63Al0.37O雙層薄膜，其所製金氧半高電子移動率電晶體之臨界電壓為-7.95V，次臨界擺幅為97.19 mV/decade，電流開關比為4.53×1010，閘極漏電流為1.27×10-13 A，最大輸出電流為633.8 mA/mm，閘極電壓擺幅為3.8 V。

In this work, 20nm HfO2 and Al2O3 films were deposited by atomic layer deposition system (ALD). Based on hafnium dioxide, alumina is doped to alter the element ratio. By modulating the ALD cycle of (HfO2)m/(Al2O3)n, , HfxAl1-xO thin films with different hafnium-aluminum ratios can be obtained. When the proportion m to n is (1/1), (3/1) and (5/1), we can obtain the Hf0.36Al0.64O, Hf0.63Al0.37O and Hf0.79Al0.21O ternary composites. After the measurement by AFM, the result displayed that alumina incorporation into HfO2 can improve surface roughness. Although the dielectric constant will decrease as the aluminum composition increases, the k-value of Hf0.63Al0.37O still remains about 19. With the alumina incorporation, the crystallization temperature is improved from 400 ºC to 800 ºC, significantly. To understand the impact of annealing on the material, samples annealed in nitrogen at 300 ºC for 5 minutes were prepared and analyzed using XPS. The analysis revealed that oxygen vacancies decreased from 14.9% initially to 8.6%. Additionally, there was improved bonding between hafnium and aluminum with oxygen. Also, the conduction band offset to GaN is increased. Finally, we deposited the HfAlO as the gate dielectric of metal oxide semiconductor high electron mobility transistors. The MOS-HEMT with (5/15 nm) ALD Al2O3/Hf0.63Al0.37O gate dielectric exhibited a Vth of -7.95, a SS of 97.19 mV/decade, an on/off current ratio of 4.53×1010, a max transconductance of 81 mS, a max drain current of 633.8 mA/mm, a gate leakage current of 1.27×10-13 A, a GVS of 3.8 V. Compared with the conventional schottky HEMT, the gate leakage current is reduced by 5 orders when the gate dielectric layer is added.

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