過去人類大量使用石化燃料，造成溫室效應、空氣汙染等環境的迫害，使得氣候變遷。能源的議題不斷浮上檯面，這是我們應該正視的議題。然而，氫能是有潛力取代石化燃料的，無論是原料的來源、燃燒後能量的多寡，還是燃燒後的產物，氫能都較石化燃料具有優勢。
本實驗是應用三五族半導體氮化鎵，做為光電化學電解水之工作電極相關特性研究。包含表面電漿原理和應用、表面形貌量測和分析、光電化學分析和應用。目的是為了提升元件的化學穩定性，以及提升照光時分解水產生氫氣、氧氣，以及將二氧化碳轉換為甲酸的效率。
氮化鎵擁有穩定的化學特性，能抗腐蝕抗酸鹼，且具有可以轉換二氧化碳的寬能隙。但是寬能隙也使得氮化鎵只能吸收紫外光波段的能量，然而紫外光占總太陽能光譜僅5%。於是我們原件上利用奈米金屬粒子的特性，金屬粒子中的電子因電磁波的影響產生震盪，粒子與粒子之間會產生共振，因而吸收特定能量。實驗中我們調整條件，使元件額外吸收可見光波段的能量，進而提升氮化鎵產生氫氣和轉換二氧化碳的能力。調整結構後，確實成功提升氮化鎵工作電極的效能，產氫效率從0.92%到1.41%；轉換二氧化碳的效率從0.16%到0.44%。
最後我們利用三項實驗進一步證明，使用表面電漿共振能夠提升氮化鎵工作電極的效能。實驗一是去除原件上的金屬粒子，以確認除了金屬粒子以外是否有其他因素造成效能提升，實驗證實此結構和材料並沒有提升效能；實驗二是去除氮化鎵所吸收的波段，利用波長大於400nm的入射光照射，檢驗元件是否能吸收可見光波段的能量，實驗證實元件的確能吸收可見光波段，且提升氮化鎵工作電極的效能。實驗三是量測IPCE，利用單色光去量測個別的光電流。

In this study, we use the Localized Surface Plasmon Resonance (LSPR) effect to enhance photocurrent density of n-type Gallium Nitride (n-GaN), and evaporate a10nm Ag film on the n-GaN substrate with E-beam evaporator. After annealing for 10 minutes at 200℃, the Ag film becomes nanoparticles with a dimeter of 30nm. Additionally, we sputter 50nm Titanium dioxide (TiO2) on the Ag nanoparticles, enabling it to absorb light with peak wavelength 550nm. However, if GaN does not contact the electrolyte, recombination of charge carriers would be incurred. In order to resolve this problem, we wet etch the LSPR structure into cyclical strip structure so that part of the exposed GaN can effectively discharge holes. With the parameter of 3x20(LSPR width 20μm and GaN width 3μm of cyclical strip structure),we obtain the best result, which is improvement from 7.86 mA/cm2 to 10.66 mA/cm2.in photocurrent density, and 0.91% to 1.41% in hydrogen production.

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