Transmission-Electron-Microscopy-Generated
Atomic
Defects in Two-Dimensional Nanosheets and Their Integration in Devices
for Electronic and Optical Sensing
posted on 2022-08-15, 12:20authored byMoritz Quincke, Tibor Lehnert, Itai Keren, Narine Moses Badlyan, Fabian Port, Manuel Goncalves, Michael J. Mohn, Janina Maultzsch, Hadar Steinberg, Ute Kaiser
For electronic and optical applications of two-dimensional
(2D)
materials and their vertical heterostructures, it is important to
know the positions, densities, and atomic structures of crystallographic
defects. Thus, to understand the role of these well-defined defects
on the properties of 2D heterostructure devices, it is desirable to
combine device measurements with atomically resolved transmission
electron microscopy (TEM) experiments. Here, the electron beam is
used not only to image atomic defects but also to create and manipulate
them. However, TEM poses special requirements to sample preparation
because it needs freestanding samples. Our presented generic sample
platform enables TEM imaging of freestanding 2D materials, followed
by experiments on the same sample area placed on an arbitrary substrate
or embedded into a heterostructure device. A sacrificial copper layer
and a hydrophobic polystyrene film enable the transfer of a strongly
adhered 2D material flake from a TEM grid to the substrate. Proof-of-principle
experiments show that signatures of electron-beam-induced defects
can be measured in electric tunneling measurements and photoluminescence.
Our transfer procedure works reliably for monolayer and few-layer
transition-metal dichalcogenides such as MoS2, MoSe2, WSe2, MoTe2, hBN, and graphene. It
can also be suitable for the assembly of defect-based sensors and
photon sources.