碩士 / 國立成功大學 / 光電科學與工程學系 / 101 / 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
| Identifer | oai:union.ndltd.org:TW/101NCKU5614008 |
| Date | January 2013 |
| Creators | Yu-TongChen, 陳育同 |
| Contributors | Jinn-Kong Sheu, 許進恭 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 95 |
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