Two-dimensional
(2D) semiconducting transition metal dichalcogenides
(TMDs) have emerged as attractive platforms in next-generation nanoelectronics
and optoelectronics for reducing device sizes down to a 10 nm scale.
To achieve this, the controlled synthesis of wafer-scale single-crystal
TMDs with high crystallinity has been a continuous pursuit. However,
previous efforts to epitaxially grow TMD films on insulating substrates
(e.g., mica and sapphire) failed to eliminate the
evolution of antiparallel domains and twin boundaries, leading to
the formation of polycrystalline films. Herein, we report the epitaxial
growth of wafer-scale single-crystal MoS2 monolayers on
vicinal Au(111) thin films, as obtained by melting and resolidifying
commercial Au foils. The unidirectional alignment and seamless stitching
of the MoS2 domains were comprehensively demonstrated using
atomic- to centimeter-scale characterization techniques. By utilizing
onsite scanning tunneling microscope characterizations combined with
first-principles calculations, it was revealed that the nucleation
of MoS2 monolayer is dominantly guided by the steps on
Au(111), which leads to highly oriented growth of MoS2 along
the ⟨110⟩ step edges. This work, thereby, makes a significant
step toward the practical applications of MoS2 monolayers
and the large-scale integration of 2D electronics.
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