本研究以簡單與低成本的製程技術製備高效能的氫氣感測元件，內文將分為兩個部分。第一部分探討不同成長溶液濃度的氧化鋅奈米柱在平面結構矽基板之氫氣感測及物性分析。接著在摻雜不同條件的石墨相氮化碳於氧化鋅奈米柱，並且成長於平面結構矽基板之氫氣感測及物性分析。第二部分則是將前述摻雜石墨相氮化碳的氧化鋅奈米柱成長在立體的金字塔結構上，再做氫氣感測及物性分析。此外，針對氫氣感測最好的試片，將其進行穩定性、重複性及選擇性量測。
研究發現，氧化鋅奈米柱在成長溶液濃度為20 mM時，擁有最小的INBE/IDLE比值，在500 ppm的氫氣濃度下，響應值為25.92%。接著在溶膠凝膠法中添加不同參數的石墨相氮化碳，旋塗在基板上作為晶種層，以此進行水熱法成長氧化鋅奈米柱，響應值明顯地提升，在500 ppm的氫氣濃度下，響應值為46.51%。造成提升的因素可能如下，第一個是石墨相氮化碳附著在氧化鋅奈米柱的表面，使整體的比表面積提升，可以為氣體吸附提供更多的活性位點，導致更好的響應值；第二個是氧化鋅與石墨相氮化碳之間形成的異質接面，因為氧化鋅與石墨相氮化碳的晶格參數不同，大量的缺陷提供了潛在的活性位點，因此與純的氧化鋅奈米柱相比，複合元件的響應值更高。
除此之外，利用濕式蝕刻法得到不同尺寸的金字塔結構，配合溶膠凝膠法與水熱法成長摻雜了石墨相氮化碳的氧化鋅奈米柱於其上。當柱體之間不再緊密相連，氣體吸附於表面的機會提升，得到更好的響應值，在500 ppm的氫氣濃度下，響應值為52.75%。

In this study, a structure of graphite carbon nitride (g-C3N4) doped zinc oxide nanorods (ZNR) was synthesized using a simple and cost-effective method. Through this method, g-C3N4 were successfully doped with ZNR. Various analyses were used to confirm the successful formation of the gCN-ZNR structure. The hydrogen sensing properties of gCN-ZNR were investigated, which shows that remarkably improved H2 sensing performances for gCN doped ZNR. In addition, the gCN-ZNR composites also exhibited outstanding stability, repeatability and selectivity.
In our experiments, we found that the response of the sensor to H2 was remarkably improved. The results about improved H2 sensing behaviors can be mainly attributed to two factors. First, the gCN-ZNR structure effectively increased the surface area that provides more active sites. This leads to rapid gas adsorption/desorption, thereby exhibit a higher response than that of pure ZNR. Another possible reason for the improved H2 response of the nanocomposite sensors may be attributed to the heterojunction between g-C3N4 and ZnO. Because of the different lattice parameters, this nanocomposite consists of defects that create enough oxygen vacancies (influence the chemical adsorption/desorption process). It was revealed that gCN-ZNR based H2 sensor exhibit response of 46.51% compared to pure ZNR (25.92%) based hydrogen sensor.
In addition to silicon plane structure, we have also studied silicon pyramid structure and grown gCN-ZNR on it. This nanocomposite sensor exhibits the superior response of 52.75%, which is better than pure ZNR (25.92%) and gCN-ZNR (46.51%). This can be attributed to the above-mentioned gCN-ZNR properties as well as three-dimensional structure of silicon pyramid substrate, which further improves the chemisorption process.

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