  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.

Materials Science