Monolayers of 2D transition metal dichalcogenides (TMDCs) provide excellent semiconducting
counterparts to insulating hexagonal boron nitride (hBN) and conductive graphene. Combining all
three materials in a Van der Waals vertical heterostructure allows the electronic, photovoltaic and
electroluminescent properties of the TMDCs to be studied. Whilst transport and optoelectronic
measurements can probe the properties of exotic charge carriers, and ARPES can map the
bandstructure such systems, direct high resolution imaging of the buried interfaces is only possible
via high resolution cross sectional (S)TEM imaging. The nature of these van der Waals interfaces
not only determines the carrier injection between components, but also affects the bandstructure
of the device and its ultimate functionality.
Here we present a novel strategy to denoise high resolution HAADF STEM images of cross sections
using principal component analysis (PCA). Cross sections are fabricated in a dual-beam FIB-SEM
instrument using the in situ lift-out method and polished with low energy ions to achieve electron
transparency. Cross sections were imaged in high resolution HAADF STEM using a probe-side
aberration corrected FEI Titan G2 80-200 kV with an X-FEG electron source. By treating each line
profile perpendicular to the fringes as a signal, components associated with noise and scattering can
be separated by their variance. Removing the noise components allows us to accurately determine
the separation between dissimilar crystals at these unique interfaces. More widely, the approach
developed here also has application in a variety of layered material systems.
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To cite this abstract:Aidan Rooney, Aleksey Kozikov, Eric Prestat, Freddie Withers, Andre Geim, Konstantin Novoselov, Sarah Haigh; Principle component analysis applied to high resolution cross sectional STEM imaging: Quantitative analysis of 2D heterostructures. The 16th European Microscopy Congress, Lyon, France. https://emc-proceedings.com/abstract/principle-component-analysis-applied-to-high-resolution-cross-sectional-stem-imaging-quantitative-analysis-of-2d-heterostructures/. Accessed: December 4, 2023
EMC Abstracts - https://emc-proceedings.com/abstract/principle-component-analysis-applied-to-high-resolution-cross-sectional-stem-imaging-quantitative-analysis-of-2d-heterostructures/