Direct Measurement of the Thermal Expansion Coefficient of Epitaxial WSe 2 by Four-Dimensional Scanning Transmission Electron Microscopy.

Autor: Kucinski TM; Center for Integrated Nanotechnologies (CINT), Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.; Nuclear Materials Science Group (MST-16), Materials and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States., Dhall R; National Center for Electron Microscopy (NCEM), The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States., Savitzky BH; National Center for Electron Microscopy (NCEM), The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States., Ophus C; National Center for Electron Microscopy (NCEM), The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States., Karkee R; Center for Integrated Nanotechnologies (CINT), Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States., Mishra A; Physics and Chemistry of Materials Group (T-1), Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States., Dervishi E; Electrochemistry and Corrosion Team, Sigma Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States., Kang JH; Department of Electrical & Computer Engineering, Seoul National University, Seoul 08826, Republic of Korea., Lee CH; Department of Electrical & Computer Engineering, Seoul National University, Seoul 08826, Republic of Korea., Yoo J; Center for Integrated Nanotechnologies (CINT), Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States., Pettes MT; Center for Integrated Nanotechnologies (CINT), Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
Jazyk: angličtina
Zdroj: ACS nano [ACS Nano] 2024 Jul 09; Vol. 18 (27), pp. 17725-17734. Date of Electronic Publication: 2024 Jun 27.
DOI: 10.1021/acsnano.4c02996
Abstrakt: Current reports of thermal expansion coefficients (TEC) of two-dimensional (2D) materials show large discrepancies that span orders of magnitude. Determining the TEC of any 2D material remains difficult due to approaches involving indirect measurement of samples that are atomically thin and optically transparent. We demonstrate a methodology to address this discrepancy and directly measure TEC of nominally monolayer epitaxial WSe 2 using four-dimensional scanning transmission electron microscopy (4D-STEM). Experimentally, WSe 2 from metal-organic chemical vapor deposition (MOCVD) was heated through a temperature range of 18-564 °C using a barrel-style heating sample holder to observe temperature-induced structural changes without additional alterations or destruction of the sample. By combining 4D-STEM measurements with quantitative structural analysis, the thermal expansion coefficient of nominally monolayer polycrystalline epitaxial 2D WSe 2 was determined to be (3.5 ± 0.9) × 10 -6 K -1 and (5.7 ± 2) × 10 -5 K -1 for the in- and out-of-plane TEC, respectively, and (3.6 ± 0.2) × 10 -5 K -1 for the unit cell volume TEC, in good agreement with historically determined values for bulk crystals.
Databáze: MEDLINE
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