Phase transformations in single-layer MoTe2 stimulated by electron irradiation and annealing
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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en
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12
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Nanotechnology, Volume 35, issue 14, pp. 1-12
Abstract
Among two-dimensional (2D) transition metal dichalcogenides (TMDs), MoTe2 is predestined for phase-engineering applications due to the small difference in free energy between the semiconducting H-phase and metallic 1T′-phase. At the same time, the complete picture of the phase evolution originating from point defects in single-layer of semiconducting H-MoTe2 via Mo6Te6 nanowires to cubic molybdenum has not yet been reported so far, and it is the topic of the present study. The occurring phase transformations in single-layer H-MoTe2 were initiated by 40-80 kV electrons in the spherical and chromatic aberration-corrected high-resolution transmission electron microscope and/or when subjected to high temperatures. We analyse the damage cross-section at voltages between 40 kV and 80 kV and relate the results to previously published values for other TMDs. Then we demonstrate that electron beam irradiation offers a route to locally transform freestanding single-layer H-MoTe2 into one-dimensional (1D) Mo6Te6 nanowires. Combining the experimental data with the results of first-principles calculations, we explain the transformations in MoTe2 single-layers and Mo6Te6 nanowires by an interplay of electron-beam-induced energy transfer, atom ejection, and oxygen absorption. Further, the effects emerging from electron irradiation are compared with those produced by in situ annealing in a vacuum until pure molybdenum crystals are obtained at temperatures of about 1000 °C. A detailed understanding of high-temperature solid-to-solid phase transformation in the 2D limit can provide insights into the applicability of this material for future device fabrication.Description
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Köster, J, Kretschmer, S, Storm, A, Rasper, F, Kinyanjui, M K, Krasheninnikov, A V & Kaiser, U 2024, 'Phase transformations in single-layer MoTe 2 stimulated by electron irradiation and annealing', Nanotechnology, vol. 35, no. 14, 145301, pp. 1-12. https://doi.org/10.1088/1361-6528/ad15bb