van der Waals Epitaxial Growth of Atomically Thin α-MoO3 on MoS2 by Oxidation

Abstract number
European Microscopy Congress 2020
Corresponding Email
[email protected]
PSA.1 - 1D & 2D Materials
Aram Yoon (2, 1), Jung Hwa Kim (1), Jongchan Yoon (2, 1), Yeongdong Lee (2, 1), Prof. Zonghoon Lee (2, 1)
1. Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS)
2. School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST)

molybdenum disulfide, thermal oxidation, transmission electron microscopy

Abstract text

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have received great interests because of their unique properties and these properties are known to be significantly influenced by oxidation. Therefore, tuning the properties using oxidation has been actively studied. However, structural instability and small quantity of oxides make difficult to elucidate the oxidation of TMDs clearly. Here, we study oxidation of 2D molybdenum disulfide (MoS2) in aspects of morphologies and phases of oxides using transmission electron microscopy (TEM) analysis. The oxidation of MoS2 is initiated along the active sites (e.g., edge, wrinkle, or native defects) as a form of orthorhombic phase molybdenum trioxide (α-MoO3) nanosheets; α-MoO3 has a layered structure with each layer composed of two rows of MoO6 octahedra. The α-MoO3 nanosheets are stacked on the underlying MoS2 with a van der Waals interaction and they aligned epitaxially. Through oxidation, we analyze that the bandgap changes of MoS2 using electron energy loss spectroscopy (EELS) and it is elevated from 1.27 to 3.0 eV via oxidation. This study can be extended to most TMDs and the oxidized TMDs will offer new strategies to be applied in various applications such as a p-type transistor, gas sensors, and photocatalysts.


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[2] Kim, J. H., Dash, J. K., Kwon, J., Hyun, C., Kim, H., Ji, E., Lee, G.-H., 2D Mater. (2018), 015016.