NSF-CGP Fellowship: Correlation of Stress with Hydrogen Microstructure and Photodegradation in Hydrogenated Amorphous Silicon

9802430 Han该奖项为查佩尔山的北卡罗来纳州大学物理和天文学系的Daxing Han博士与日本岐阜大学电气工程系的Shoji Nitta博士合作进行为期3个月的研究访问提供资金。 这两位合作者将研究氢化非晶硅（a-Si：H）中光致应力变化及其与氢微结构以及电子缺陷态密度的相关性。 这种材料a-Si：H是薄膜晶体管阵列的主要候选材料，可用于驱动大面积平板显示器，开发太阳能电池清洁能源，以及大面积光电传感器阵列。 已经发现，常规的非氢稀释辉光放电本征材料具有非常高的应力。 这种材料显示出光降解，但其稳定的性能对于大面积器件如太阳能电池仍然相当好。 然而，还不清楚应力是否与光诱导亚稳性相关，或者应力是否与a-Si：H中的氢微结构相关。 最近的研究结果表明，在传统的辉光放电过程中通过氢稀释和通过热灯丝辅助化学气相沉积技术，a-Si：H太阳能电池的稳定性得到了显着改善。岐阜大学的研究小组最近开发了一种创新的工具，原子力显微镜，利用弯曲梁方法，它对弱应力敏感，如在薄石英上沉积的a-Si：H中光诱导应力的变化。 这些更稳定的“新”非晶硅材料和创新工具为阐明应力和氢微观结构之间的相关性以及a-Si：H中的电子特性提供了独特的机会。 拟议的调查将有助于提供一个深入了解的亚稳性的微观结构起源，并提高在这个非晶硅网络的结构和电子状态之间的相关性的证据。 该项目由国家科学基金会和日本基金会全球伙伴关系中心之间的科学奖学金计划提供支持。

9802430HanThis award provides funds to support a 3-month research visit by Dr. Daxing Han, Department of Physics and Astronomy, University of North Carolina at Chapel Hill, for collaboration with Dr. Shoji Nitta, Department of Electrical Engineering, Gifu University, Japan. These two collaborators will investigate the photo-induced changes on stress and its correlation with hydrogen microstructure as well as the density of electronic defect states in hydrogenated amorphous silicon (a-Si:H). This material, a-Si:H, is a leading candidate for thin film transistor arrays to drive large-area flat panel displays and for the development of clean energy from solar cells, as well as for large-area photo-sensor arrays. It has been found that the conventional, non-hydrogen diluted glow discharge intrinsic material has very high stress. This material shows photo-degradation, but its stabilized properties are still quite good for large area devices such as solar cells. It has been unclear, however, whether the stress is correlated with the light-induced metastability, or whether there is a correlation of stress with hydrogen microstructures in a-Si:H. Recent results indicate that significant improvement in stability of a-Si:H solar cells has been made by hydrogen dilution during the conventional glow discharge and by the hot filament assisted chemical vapor deposition technique.The research group at Gifu University recently developed an innovative tool, the atomic-force-microscope, utilizing a bending-beam method, that is sensitive to weak stress such as the light-induced changes of the stress in a-Si:H deposited on thin quartz. These more stable "new" amorphous-silicon materials and the innovative tool offer a unique opportunity to elucidate the correlation between the stress and hydrogen microstructure as well as the electronic properties in a-Si:H. The proposed investigations will help provide an insight into the microstructure origin of the metastability and enhance the evidence for the correlation between structural and electronic states in this amorphous silicon network. This project is supported under the Science Fellowship Program between the National Science Foundation and the Japan Foundation Center for Global Partnership.***