Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, People's Republic of China. CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China.
Nanotechnology. 2019 May 17;30(20):205702. doi: 10.1088/1361-6528/ab0452. Epub 2019 Feb 4.
Interfacial engineering, such as molecule intercalation, can modify properties and optimize performance of van der Waals heterostructures and their devices. Here, we investigated the pristine and water molecule intercalated heterointerface of niobium disulphide (NbS) on hexagonal boron nitride (h-BN) (NbS/BN) using advanced atomic force microscopy (AFM), and observed the metal-insulator transition (MIT) of first layer (1L-) of NbS induced by water molecule intercalation. In pristine sample, interfacial charge transfers were confirmed by the direct detection of trapped static charges at the post-exposed h-BN surface, produced by mechanically peeling off the 1L-NbS from the substrate. The interfacial charge transfers facilitate the intercalation of water molecules at the heterointerface. The intercalated water layers make a MIT of 1L-NbS, while the pristine metallic state of the following NbS layers remains preserved. This work is of great significance to help understand the interfacial properties of 2D metal/insulator heterostructures and can pave the way for further preparation of an ultrathin transistor.
界面工程，如分子插入，可以改变范德华异质结构及其器件的性质和优化性能。在这里，我们使用先进的原子力显微镜（AFM）研究了二硫化铌（NbS）在六方氮化硼（h-BN）上的原始和水分子插入异质界面（NbS/BN），并观察到水分子插入诱导的第一层（1L-）NbS 的金属-绝缘体转变（MIT）。在原始样品中，通过机械剥离衬底上的 1L-NbS，直接检测到在暴露后的 h-BN 表面上捕获的静电荷，可以证实界面电荷转移。界面电荷转移促进了异质界面上水分子的插入。插入的水层使 1L-NbS 发生 MIT，而随后的 NbS 层仍保持原始的金属态。这项工作对于帮助理解二维金属/绝缘体制备超薄膜晶体管的异质结构的界面性质具有重要意义。
