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Medientyp:
E-Artikel
Titel:
High-Speed Imaging of Second-Harmonic Generation in MoS2 Bilayer under Femtosecond Laser Ablation
Beteiligte:
Kim, Young Chul;
Yoo, Hoseong;
Nguyen, Van Tu;
Lee, Soonil;
Park, Ji-Yong;
Ahn, Yeong Hwan
Erschienen:
MDPI AG, 2021
Erschienen in:Nanomaterials
Sprache:
Englisch
DOI:
10.3390/nano11071786
ISSN:
2079-4991
Entstehung:
Anmerkungen:
Beschreibung:
<jats:p>We report an in situ characterization of transition-metal dichalcogenide (TMD) monolayers and twisted bilayers using a high-speed second-harmonic generation (SHG) imaging technique. High-frequency laser modulation and galvano scanning in the SHG imaging enabled a rapid identification of the crystallinity in the TMD, including the orientation and homogeneity with a speed of 1 frame/s. For a twisted bilayer MoS2, we studied the SHG peak intensity and angles as a function of the twist angle under a strong interlayer coupling. In addition, rapid SHG imaging can be used to visualize laser-induced ablation of monolayer and bilayer MoS2 in situ under illumination by a strong femtosecond laser. Importantly, we observed a characteristic threshold behavior; the ablation process occurred for a very short time duration once the preheating condition was reached. We investigated the laser thinning of the bilayer MoS2 with different twist angles. When the twist angle was 0°, the SHG decreased by approximately one-fourth of the initial intensity when one layer was removed. Conversely, when the twist angle was approximately 60° (the SHG intensity was suppressed), the SHG increased abruptly close to that of the nearby monolayer when one layer was removed. Precise layer-by-layer control was possible because of the unique threshold behavior of the laser-induced ablation.</jats:p>