基于界面自组装法构筑“二维纳米晶体/一维氧化锌阵列”复合型光探测器及其性能研究

It is an emerging requirement and hot topic to develop novel functional nanomaterials and fabrication technology for high-performance microelectronic and optoelectronic devices. Most recently, we have developed an "oil-water interfacial self-assembly" strategy as a low-cost and effective method to construct nanofilm-based photodetectors. However, the photodetectors constrcuted from this route generally shows low sensivitity and low external quantum efficency (EQE). In the present project, a novel photodetector based on nano-heterostructure is proposed to deal with this problem. We will self-assemble two-dimensional (2D) semiconducting nanocrystals into a high-quality nanofilm using the "oil-water interfacial self-assembly" strategy, and then one-dimensioanl (1D) ZnO nanowire arrays will be eptiaxially grown on these 2D nanocrystals by a wet-chemical technology. A type-II heterostructure will be rationally designed in this "2D nanocrystal/1D ZnO nanoarrays", which is favorable for the spatial separatation of photogenerated carries and enhancement of EQE value for photoresponse. Sebsequently, photodetectors with a sandwich structure will be constructed based on this "2D nanocrystal/1D ZnO nanoarrays" composite and their optoelectronic properties will be studied in detail. The propose of this study is to design novel semiconducting nanostructures and develop facile strategy to fabricate high-performance optoelectronic nanodevices, to understand the growth mechanism for 2D/1D nano-heterostructure, and to reveal their "composition-structure-morphology-properties" relatives and principles. We believe that the success of this study should provide a new and low-cost way to fabricate a series of nanofilm-based photodetectors with high photoresponse sensitivity and EQE, and provide theoretic foundation for the development of thin-film based nanodevices.

开发新型功能材料和制备工艺以用来构筑高品质高性能的纳米光探测器，是目前微电子与光电子器件领域的前沿与热点课题。近几年新出现的"油水界面自组装"技术为纳米薄膜型光探测器的制造提供了一条低成本、高效率的途径。然而，该新型工艺仍然存在灵敏度和量子效率低等局限性。本研究设计出纳米异质结构来解决上述问题，拟采用"油水界面自组装"工艺自组装二维半导体纳米结构；在自组装得到的二维纳米薄膜上采用水溶液法外延生长一维氧化锌阵列，形成有利于光生载流子分离的异质结能带结构；并基于"二维纳米晶体/一维氧化锌纳米线阵列"构筑光电器件，研究其光探测性能并提高其量子效率。本研究将设计新型半导体纳米结构，开辟新的方法来制造高品质的纳米光电器件，探索"二维/一维"纳米异质结的生长机理，揭示其 "成分-结构-形貌-物性"之间的关联性，从而为高灵敏度、低成本纳米薄膜光电器件的制造提供一条崭新的途径。

本项目针对自组装得到的薄膜型光电探测器件存在灵敏度和量子效率低等局限性，结合界面自组装方法，设计出二维纳米异质结以形成有利于光生载流子分离的能带结构，从而提高器件的综合性能。通过材料体系与工艺路线的合理选择与优化，分别构筑了基于“ZnO纳米线阵列”、““二维CuGaO2纳米六角片/ZnS 纳米微球”pn结复合阵列”、“Mg离子掺杂 NiO单层碗状薄膜”、“Zn2SnO4纳米方块阵列”等薄膜型光探测器件，通过pn结内建电场的调控作用和金属离子的掺杂，显著提高了器件在灵敏度和量子效率等性能指标。研究发现，对于油水界面自组装方法构筑的Ni0.8Mg0.2O纳米碗状薄膜基纳米器件，在偏压为10 V时灵敏度为6.76 A/W，外量子效率值为2620%，是前人报道Ni0.8Mg0.2O薄膜数值的6,000倍。.以上工作探索了二维纳米异质结薄膜的生长机理及光电性能，寻找到了“自组装薄膜型器件灵敏度和量子效率偏低”等科学问题的解决方法，揭示其 “成分-结构-形貌-物性”之间的关联性, 为高灵敏度、低成本纳米薄膜光电器件的制造提供一条崭新的途径。在本项目资助下，总共在Adv. Funct. Mater.、Adv. Energy Mater.、Small、J. Mater. Chem. A 等材料学科的主流国际期刊上发表含本项目基金号的SCI一区论文27篇（Adv. Funct. Mater.9篇，Small 3篇，Adv. Energy Mater. 2篇），其中影响因子大于10.0的论文11篇，两篇论文选作Adv. Funct. Mater.期刊的封面，有7篇论文入选ESI高被引论文，有一篇论文被评选为“2014年度中国百篇最具影响国际学术论文“。研究结果被Materials Today 2014, 2, 771杂志给予highlight专题报道。