Using four-dimensional scanning transmission electron microscopy, we demonstrate a method to visualize grains and grain boundaries in WSe2grown by metal organic chemical vapor deposition (MOCVD) directly onto silicon dioxide. Despite the chemical purity and uniform thickness and texture of the MOCVD-grown WSe2, we observe a high density of small grains that corresponds with the overall selenium deficiency we measure through ion beam analysis. Moreover, reconstruction of grain information permits the creation of orientation maps that demonstrate the nucleation mechanism for new layers-Triangular domains with the same orientation as the layer underneath induces a tensile strain increasing the lattice parameter at these sites.
Bibliographical noteFunding Information:
This work was supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory under project numbers 20190516ECR, 20210036DR, 20220485MFR, and 20210782ER, and the National Security Education Center under project numbers IMS RR19PETT, IMS RR21PETT, and ISTI IP2104MP. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract no. DE-AC02-05CH11231. C.O. acknowledges additional support from the Department of Energy Early Career Research Award program. C.-H.L. acknowledges support from the National Research Foundation (NRF) of Korea (2020M3D1A1110548) and the KU-KIST School Project. This work was performed in part at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Los Alamos National Laboratory, an affirmative action equal opportunity employer, is managed by Triad National Security, LLC for the U.S. Department of Energy’s NNSA, under contract 89233218CNA000001.
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- 2D materials
- grain boundaries
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Mechanical Engineering