Jie Yanni, Wang Dong, Huang Jianfeng, Feng Yongqiang, Yang Jun, Fang Jiawen, Chen Runfeng
School of Materials Science & Engineering, Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic Materials, Shaanxi University of Science and Technology, Xi'an 710021, China.
State Key Laboratory of Organic Electronics and Information Displays, Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, China.
ACS Appl Mater Interfaces. 2022 Jan 12;14(1):1609-1614. doi: 10.1021/acsami.1c21079. Epub 2021 Dec 28.
Electronic transport through molecular-scale devices has been studied extensively for its extraordinary dimension superiority. Assembling such devices into large-scale functional circuits is crucial since the molecular tunnel junctions must be reliable, stable and reproducible during technological applications. In ideal circumstances, the device architecture should be designed such that the metal-molecule-metal (MMM) junctions can be analyzed by the more sensitive four point probe system. In this paper, we expound a delicate method to manufacture molecular junctions, which show excellent stability and reproducibility with high yields (91 per cent). We form self-assembled monolayers (SAMs) on conductive Au thin film by microcontact printing and then generate robust covalently bound metal thin film electrodes on top of the SAMs by selective electroless deposition. Following MMM junction formation, a photoresist is coated and wells are opened on each feature by lithography. Then, Au thin film, as a permanent top electrode, is deposited into the photolithographically defined well. Conductivity analyzations were carried out on the 50 μm square junctions by the four point probe measurement, and the results showed reproducible tunneling - characteristics. This method reveals an approach not only offering a unique vehicle to investigate the electrical properties of molecule ensembles in MMMs, but also making a significant step toward MMM applications at the device level.
由于其非凡的尺寸优势，通过分子尺度器件的电子输运已得到广泛研究。将此类器件组装成大规模功能电路至关重要，因为在技术应用过程中，分子隧道结必须可靠、稳定且可重复。在理想情况下，器件架构的设计应使金属 - 分子 - 金属（MMM）结能够通过更灵敏的四点探针系统进行分析。在本文中，我们阐述了一种制造分子结的精细方法，该方法具有出色的稳定性和可重复性，产率高达91%。我们通过微接触印刷在导电金薄膜上形成自组装单分子层（SAMs），然后通过选择性化学沉积在SAMs顶部生成坚固的共价键合金属薄膜电极。在形成MMM结之后，涂覆光刻胶并通过光刻在每个特征上开孔。然后，将金薄膜作为永久性顶电极沉积到光刻定义的孔中。通过四点探针测量对50μm方形结进行电导率分析，结果显示出可重复的隧穿特性。该方法不仅揭示了一种研究MMM中分子集合体电学性质的独特途径，而且朝着器件级MMM应用迈出了重要一步。
