IMDEA Nanoscience, Ciudad Universitaria de Cantoblanco, c\Faraday 9, 28049 Madrid, Spain.
Nanoscale. 2018 May 3;10(17):7966-7970. doi: 10.1039/c8nr01045e.
van der Waals heterostructures (vdWH) are made of different two-dimensional (2D) layers stacked on top of each other, forming a single material with unique properties that differ from those of the individual 2D constituent layers, and that can be modulated through the interlayer interaction. These hetero-materials can be artificially made by mechanical stamping, solution processing or epitaxial growth. Alternatively, franckeite has been recently described as an example of a naturally-occurring vdWH that can be exfoliated down to nanometer thicknesses. Research on vdWHs has so far been limited to manually exfoliated and stamped individual devices. Here, a scalable and fast method to fabricate vdWH nanodevices from liquid phase exfoliated nanoflakes is reported. The transport and positioning of the flakes into localized submicrometer structures is achieved simultaneously in multiple devices via a dielectrophoretic process. The complex vdWH is preserved after dielectrophoresis and the properties of the resulting field-effect transistors are equivalent to those fabricated via mechanical exfoliation and stamping. The combination of liquid phase exfoliation and dielectrophoretic assembly is particularly suited for the study of vdWHs and applications where large-scale fabrication is required.
范德瓦尔斯异质结构（vdWH）由不同的二维（2D）层堆叠而成，形成一种具有独特性质的单一材料，这些性质不同于单个 2D 组成层的性质，并且可以通过层间相互作用进行调制。这些异质材料可以通过机械冲压、溶液处理或外延生长来人工制造。或者，franckeite 最近被描述为一种自然存在的 vdWH 的例子，可以将其剥离到纳米厚度。到目前为止，对 vdWH 的研究仅限于手动剥离和冲压的单个器件。在这里，报道了一种从液相剥离的纳米片中制造 vdWH 纳米器件的可扩展和快速方法。通过介电泳过程，可以同时在多个器件中将薄片传输并定位到局部亚微米结构中。介电泳后保留了复杂的 vdWH，并且所得场效应晶体管的性能与通过机械剥离和冲压制造的性能相当。液相剥离和介电泳组装的结合特别适合 vdWH 的研究和需要大规模制造的应用。
