本論文研究氮化鋁鎵的材料特性以及對於紫外光二極體的相關應用，近年　本論文研究氮化鋁鎵的材料特性以及對於紫外光二極體的相關應用，近年來隨著紫外光二極體產業的發展使得氮化鋁鎵材料日益受到重視，而氮化鋁鎵具有薄膜臨界厚度小、對缺陷容忍度低、材料臨界應力低、P型摻雜不易等材料問題。我們研究使用反應式電漿鍍膜的方式成長RPD(reactive plasma deposition)-AlN以及使用有機金屬化學氣相沉積法的方式成長HT(high temprature)-AlN，比較以兩種不同方式來成長的AlN緩衝層晶體品質差異，以及製作為發光二極體元件來比較緩衝層的差異對於元件特性的影響。我們發現RPD-AlN在材料特性上相較於HT-AlN具有材料結晶性較佳、晶體缺陷較少、薄膜表面較平整等優點，這些優點使得RPD-AlN相較於HT-AlN比較適合作為緩衝層的選擇。另外，對於氮化鋁鎵的材料臨界應力低而導致材料容易具有表面裂紋的問題，我們在磊晶結構中加入以AlGaN/AlN組成的超晶格結構(Superlattic Structure)成功減緩不同磊晶層間的晶格不匹配、減少因為材料應力所造成的表面裂紋。改善上述的材料問題之後，我們進一步將RPD-AlN應用於傳統結構(P-I-N)發光二極體並且成功調整為波長320nm的紫外光發光二極體，並且由於晶體品質獲得改善因此發光效率獲得大幅提升。
另一方面，不同於P-I-N結構發光二極體中，是將電子、電洞由MQW異側注入複合，我們成功將載子擴散輔助(Diffusion-Assisted，D-A)結構應用於紫外光二極體，將電子、電洞由MQW同側擴散注入複合，預期將改善P-I-N結構的載子溢流效應對於發光效率的不良影響，此實驗概念已經在藍光二極體的實驗結果中獲得驗證。然而，實際應用於紫外光二極體中，由於D-A結構需要額外的能量來克服n-GaN/p-AlGaN的能隙差異、加上電子需要跨越p-AlGaN來注入MQW，這些能量消耗反而助長元件熱效應而導致D-A結構的發光效率低於PIN結構。未來我們將嘗試以Si離子佈植的方式取代選擇性再成長的方式來製作D-A結構的紫外光二極體，希望藉由Si離子佈植方式產生n-AlGaN/p-AlGaN將不再具有能隙差異，同時可以降低電子跨越p-AlGaN注入MQW所需要的能量，預期以Si離子佈植的方式取代選擇性再成長的方式製作D-A結構紫外光二極體將可以使發光效率獲得提升。

In this study, we demonstrated the UV-LEDs with reactive plasma deposited (RPD) AlN and high temperature (HT) AlN nucleation layer. We found that reactive plasma deposited AlN film has flat surface roughness and high crystal quality. Furthermore, we developed that AlGaN/AlN superlattic structure were grown on AlN nucleation layer, it can significantly reduce dislocation density and cracks caused by differences in the lattice constant. Therefore, we applied above methods to fabricate AlGaN-based UV-LEDs of 320nm and the light output power is enhanced. On the other hand, we applied diffusion-assisted (D-A) way in UV-LEDs. Although the light output power of the D-A LEDs is less than the traditional LEDs at present. We believed it was a potential way to improve efficiency drop of the traditional LEDs caused by carrier leakage.

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