過去幾年來人類大量使用石化燃料排放溫室氣體，除了造成石化礦產資源短缺和價格攀升之外，地球環境也深深地受到溫室氣體影響波即到下一世代人類的生活。因此除了找尋其他替代能源之外，其使用上也必須是能夠再生利用且對環境友善的，氫能就是解決的方法之一。
本研究主要探討應用三族氮化物半導體當作光電化學電解水工作電極的相關特性，內容包含元件材料特性、磊晶結構、電化學分析與半導體製程等相關理論的結合與應用，目的就是希望提升元件的化學穩定性以及照光時分解水分子生成氫氣與氧氣的速率。
縱使氮化鎵材料對於酸鹼溶液具有良好的抗腐蝕特性且該材料能隙大小也符合水分子的氧化還原電位，然而其對應所能吸收的入射光限於紫外光波段，占總太陽光譜約僅5%。於是我們於元件結構上摻雜過度元素錳，目的是藉此方式於禁止帶中生成雜質能階，增加可見光波段的吸。最後確實成功改善錳摻雜元件的電性之外，也實現元件對長波段的吸收提升產氫速率。
氮化鎵材料與藍寶石基板之間晶格不匹配相當嚴重，常會造成磊晶結構為了化解內應力而產生線缺陷。為此已經發展出一套選擇性成長的磊晶技術，透過遮罩的方式產生側向成長阻止線缺陷向上延伸。我們應用離子佈植的方式進行選擇性成長規則型圖案結構，目的是增加半導體與電解液的接觸面積。然而佈植區域的晶格缺陷會降低元件品質與工作效率，因此我們以蝕刻方式成功改善晶格造成的缺陷，並且之中也探討規則形圖案的排列方式對光電流的影響。
最後我們於InGaN-based元件上成長一層氮化(鋁)鎵材料，由於磊晶層之間晶格不匹配產生的內應力造成能帶傾斜，而應用於工作電極有助於電子電洞對的分離。我們分別比較氮化鎵材料與氮化鋁鎵對InGaN-based元件的影響，實驗成功運用材料內應力產生壓電極化助於載子的萃取，並且提升光電流數值約100倍。之中我們也觀察元件表面的腐蝕情況，了解光電解對表面磊晶層的影響。

關鍵字:光電化學; 氮化鎵; 壓電場; 離子佈植

Recently, the tremendous demand and increasing usage of the fossil fuel have contributed to high cost and depletion of fossil reserves. In addition, it would result in expense of environment and human health. Actually, large productions amount of carbon dioxide, methane and chlorofluorocarbons (CFCs) lead to global warming and greenhouse effect. Therefore, it is urgent to discover other renewable energy resource, which is friendly to environment. Hydrogen generation is a solution and a key issue for this thesis.
In this thesis, we discuss the application of III-Nitride semiconductor on photoelectrolysis of water. We considered properties of materials, epitaxial structures, electrochemical analysis and semiconductor process. We purpose to make the enhancement of hydrogen generation rate and chemical reliability.
Gallium nitride materials possess appropriate band edges for redox potential of water splitting and anti-corrosion in aqueous solutions. However, the corresponding light wavelength to gallium nitride energy band gap is 365nm, contributing only about 5% of the solar spectrum can be absorbed. As a result, we demonstrated and improve the quality of Mn doped GaN as photoelectrode, and extend the absorption spectrum of GaN to visible light.
Owing to the severe lattice miss match between GaN and sapphire substrate, it exists threading dislocation in crystal structure. We successfully demonstrated patterned devices by selective ion implantation and regrowth without dielectric mask. In second part, we applied period patterned structures to increase reaction area in electrolyte. However, the ion implantation destroyed lattice structure and decreased the device quality. Accordingly, we recover the lattice defects by dry etching effectively. And we also realized the effects of pattern arrays on photocurrent density.
Finally, we achieve enhanced photocurrent density in InGaN-based PEC electrodes, and accomplish zero-bias photoelectrolysis of water under visible illumination. We successfully grew n-(Al)GaN materials upon InGaN absorption layer by MOVPE, and engineer surface band bent which result in internal electric field and facilitating hydrogen generation directly. The photocurrent and hydrogen generation rate in n-AlGaN caped device is about 100 times than that in reference n-InGaN working electrode under zero bias. Actually, we also discussed the corrosion phenomena on devices surface through SEM images.

Key words: Photoelectrochemical; GaN; Piezoelectric field; Ion implantation

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