| 학회 | 한국재료학회 |
| 학술대회 | 2015년 가을 (11/25 ~ 11/27, 부산 해운대그랜드호텔) |
| 권호 | 21권 2호 |
| 발표분야 | G. 나노/박막 재료 |
| 제목 | Hydrogen Doped ZnO as a Transparent Conductor by Photochemical Dissocation of Water Molecules |
| 초록 | The charge transport mechanism through photochemical tuning in metal-oxide semiconductors is of great interest since it may offer a facile but effective semiconductor-to-metal transition and better conductivity. This electrical property change is mainly due modification of surface and bulk electronic structure of oxides. Among many metal oxides, ZnO has various advantages such as low manufacturing cost, relatively stable surfaces, and great tunability of surface conductivity by post anneal process. Furthermore, the highly conductive ZnO can be applied to the transparent electrode in the visible light region due to its ultraviolet range band gap. Absorption or emission of light in the wide photon range from the blue region to the ultraviolet region of ZnO are possible is ideal for a broad light-emitting diodes, optical filters, optical detectors, and solar cells. In spite of these merits of ZnO, the application of ZnO as the transparent electrode still requires improved electrical conductivity without transparency degradation. In this study, ZnO surface electronic structure was modified by anneal process in vacuum and exposing to UV light which improves the surface conductivity of ZnO. From experimental results, we confirmed that the ZnO thin film of anneal process is polycrystalline. UV exposure of the ZnO surface in air promotes a photochemical surface reaction with H incorporation selective to surface-localized metal–OH complex layer formation, which acts as a tunable and stable degenerated n-type doping channel and turns ZnO to a transparent conductor. This is believed to act as strong n-type donor providing excess conduction electrons in ZnO surface. The surface electronic structure of UV-exposed ZnO did not affect the visible light absorption and transparency. Regardless of the initial resistivity of ZnO samples prepared by varying RF sputtering conditions, the electrical conductivity was improved by up to x1000. And it was found that, the H doping is more effective for the annealed samples compared to un-annealed one. The preliminary physical mechanism is also suggested to explain the origin of photochemical tunability of ZnO by UV photochemistry. We demonstrated successful applications of photochemical and highly n-doped metal oxide converted via optical dose control to transparent conductors with excellent chemical and optical doping-effect stability. |
| 저자 | 서형탁, 이상연, 김진서 |
| 소속 | 아주대 |
| 키워드 | ZnO; Hydrogen; UV exposure; surface |
