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Nanoprobing of MoS2 by Synchrotron Radiation When van der Waals Epitaxy is Locally Invalid
L. Lee, S.-Y. Tang, J.-H. Chen, T.-Y. Su, H.-C. Chen, C.-H. Lin, C.-Y. Chiang, S.-J. Chiu, C.-S. Ku, J.-L. Shen, Z. M. Wang*, and Y.-L. Chueh*
In this work, we demonstrated nano-scaled Laue diffractions by a focused polychromatic synchrotron radiation beam to discover what happens in MoS2 when van der Waals epitaxy is locally invalid. A stronger exciton recombination with a local charge depletion in the density of 1 × 1013 cm–2, extrapolated by Raman scattering and photoluminescence, occurs in grains, which exhibits a preferred orientation of 30° rotation with respect to the c-plane of a sapphire substrate. Else, the charge doping and trion recombination dominate instead. In addition to the breakthrough in extrapolating mesoscopic crystallographic characteristics, this work opens the feasibility to manipulate charge density by the selection of the substrate-induced disturbances without external treatment and doping. Practically, the 30° rotated orientation in bilayer MoS2 films is promoted on inclined facets in the patterned sapphire substrate, which exhibits a periodic array of charge depletion of about 1.65 × 1013 cm–2. The built-in manipulation of carrier concentrations could be a potential candidate to lateral and large-area electronics based on 2D materials.