New method developed for nanoscale materials characterization

Press/Media: STE Highlight

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Shown is the electron scattering from the pristine surface of a continuous monolayer tungsten diselenide film. The 4D-STEM method provides for the analysis of statistically relevant information on grain size, orientation and lattice parameters without the sample’s physical or chemical alteration. (Image credit: Sarah Tasseff, Los Alamos National Laboratory)

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In a recent cover article in the journal Nano Letters, a Los Alamos research team led by Michael Pettes (MPA-CINT) has developed a new method to obtain the local crystalline arrangement of solid materials and their imperfections from areas smaller than a nanometer. The method uses four-dimensional scanning transmission electron microscopy (4D-STEM), a materials characterization technique new to LANL that was debated whether it would be sensitive enough to resolve this information. The approach fills an important void in the characterization of mission-relevant materials and can be used to fill in the local “messy” atomic length-scale regime information that other important characterization techniques, such as beam lines, fail to provide.

The 4D-STEM technique provides a method to visualize grains and grain boundaries in tungsten diselinide (WSe2) grown by metal organic chemical vapor deposition directly onto a glass substrate, silicon dioxide.  The 4D-STEM technique can analyze statistically relevant information on grain size, orientation and lattice parameters without physical or chemical alteration of the sample, allowing for simultaneous strain and orientation mapping. The method is based on patterned-probe 4D-STEM and is the first demonstration of true transmission electron microscopy-based automated crystal orientation mapping at the nanoscale. The success of the new technique holds implications for significant follow-on impact in the field of nanoscale materials characterization.

Application-relevant, wafer-scale two-dimensional materials are usually polycrystalline. One of the major challenges in structural analysis resides in accurately identifying the grain boundary orientation and size distribution over a wide field of view, with enough spatial resolution to capture tens-of-nanometer sized domains. 4D-STEM now enables the fast collection of nano-beam electron diffraction patterns on a two-dimensional array of spatial positions. Various computational analyses can then reveal structural variations on a pixel-by-pixel basis over different scales while reducing knock-on damage in these traditionally hard-to-characterize samples.

Funding and mission

This work was supported by the Laboratory Directed Research and Development program and the National Security Education Center at Los Alamos National Laboratory. The work supports the Global Security mission area and the Materials for the Future capability pillar.

Reference

“Visualizing Grain Statistics in MOCVD WSe2 through Four-Dimensional Scanning Transmission Electron Microscopy,” Nano Letters 22, 6, 2578 (2022). DOI: 10.1021/acs.nanolett.1c04315. Authors: Alejandra Londoño-Calderon, Matthew Schneider, Yongqiang Wang, Enkeleda Dervishi, Jinkyoung Yoo, Michael T. Pettes (Los Alamos National Laboratory); Rohan Dhall, Colin Ophus (Lawrence Berkeley National Laboratory); Hee Seong Kang, Chul-Ho Lee (Korea University).

Technical Contact: Michael Pettes

PeriodJun 27 2022

Media coverage

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Media coverage

  • TitleNew method developed for nanoscale materials characterization
    Date06/27/22
    PersonsMichael Thompson Pettes, Alejandra Londono Calderon, Matthew M. Schneider, Yongqiang Wang, Enkeleda Dervishi-Whetham, Jinkyoung Yoo, Rohan Dhall, Colin Ophus, Hee Seong Kang, Chul Ho Lee, Alejandra Londono Calderon, Enkeleda Dervishi-Whetham, Rohan Dhall, Colin Ophus, Hee Seong Kang, Chul Ho Lee

Media Type

  • STE Highlight

Keywords

  • LA-UR-22-26081

STE Mission

  • Global Security

STE Pillar

  • Materials for the Future

STE Publication Year

  • 2022