Abstract
Two-dimensional (2D) transition metal dichalcogenides (TMD) have attracted intensive research attention due to their attractive properties, such as direct band gap in the visible frequency range, pronounced spin– orbit coupling, ultra-strong Coulomb interaction, and the rich physics associated with the valley degree of freedom. The ability to grow large, high-quality single crystals of 2D TMD components is essential for exploring industrial application of the materials, such as in 2D functional devices. Presently, the size of 2D TMDs single crystals is typically limited to less than one millimetre, mainly because of the difficulties in growing of such crystals, where excessive nucleation precludes growth from a single nucleus to large single crystals and the symmetry of the TMD lattice leads to antiparallel domains and twin boundaries on most substrates.
In this work, the atomic structure, electronic properties and defects of TMDs grown on vicinal substrates and metal monocrystal substrates will be reported, with particular attention to how to prepare large scale and monocrystalline TMDs. More specifically, the TMD epifilms on different substrates have been investigated by scanning tunnelling microscopy/spectroscopy (STM/S), and X-ray photoelectron spectroscopy (XPS), pointing to ways to achieving high-quality large-sized samples.
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