本論文主要是利用三族氮化物半導體材料當作光電解水產氫的工作電極，在照光的情況下將水分解成氫氣與氧氣。除了透過外部製程的改良、也從磊晶結構方面去做不同的變化，來增進氫氣產生的效率。
首先在n型氮化鎵(n-GaN)工作電極之歐姆電極上製做指叉狀浸入式電極的設計，來增加光載子的汲取效率與增強電場對工作電極的活化效果。同時我們比較金屬鉻金(Cr/Au)與氧化銦錫(ITO)浸入式電極兩種材料的優缺點，發現Cr/Au電極在光電化學(PEC)反應後幾乎損毀，而ITO電極不僅透光，且在長時間反應下結構仍然很完整、穩定性佳。因此，我們也把ITO浸入式電極應用在高電阻率的p型氮化鎵(p-GaN)上，成功地提高了光電流密度，同時也能降低產氫電壓。也因為p-GaN具有不會被光腐蝕(Photo corrosion)的特性，所以我們更可以利用增加光強度的方式來提高光電流密度，加速氫氣產生速率。
另外，我們在氮化鎵磊晶時摻入過渡元素錳(Mn)，發現其產生的雜質能帶可使材料吸收能量小於氮化鎵能隙(3.4 eV)的光子，並且能夠在可見光照射之下產生氫氣。然而，雖然摻雜錳使得材料的吸收光譜變寬，但因為其高電阻率與材料品質下降，也導致光載子容易被復合，使元件在全波段照射時之光電化學特性比沒有摻雜錳的元件來得差。

Ⅲ- Nitrides Semiconductor was used as working electrodes to generate hydrogen gas through water splitting under illumination. In this study, we promoted the efficiency of hydrogen generation by improving the processes and varying epitaxy structure.
First, immersed ohmic electrodes were fabricated on n-type Gallium Nitride (n-GaN). This design can improve the collection efficiencies of photo-generated carriers and enhance the activation effect of the electric field on working electrodes. Simultaneously, we compared the performance of immersed finger-type Cr/Au and ITO ohmic electrodes for the photoelectrochemical (PEC) reaction. We found that the immersed finger-type Cr/Au ohmic electrodes were damaged. In contrast, the immersed finger-type ITO ohmic electrodes were both transparent and stable. Therefore, we also used immersed finger-type ITO ohmic electrodes to increase the photocurrent density and reduce the applied voltage for hydrogen generation of p-GaN working electrodes. Because p-GaN had no photo corrosion after PEC reaction, the photocurrent density could be improved via intense light irradiation.
On the other hand, Mn elements were doped in u-GaN samples. By this way, the sample could absorb the photons with smaller energy than the energy band gap of GaN (3.4 eV) and generate hydrogen gas under visible light irradiation. Although Mn-doped GaN has broader absorption spectrum than GaN materials, the higher resistivity and worse crystal qualities resulted in inferior PEC characteristics under entire spectrum illumination.

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