A library of atomically thin metal chalcogenides

Abstract

Investigations of two-dimensional transition-metal chalcogenides (TMCs) have recently revealed interesting physical phenomena, including the quantum spin Hall effect, valley polarization and two-dimensional superconductivity , suggesting potential applications for functional devices. However, of the numerous compounds available, only a handful, such as Mo- and W-based TMCs, have been synthesized, typically via sulfurization, selenization and tellurization of metals and metal compounds. Many TMCs are difficult to produce because of the high melting points of their metal and metal oxide precursors. Molten-salt-assisted methods have been used to produce ceramic powders at relatively low temperature and this approach was recently employed to facilitate the growth of monolayer WS and WSe. Here we demonstrate that molten-salt-assisted chemical vapour deposition can be broadly applied for the synthesis of a wide variety of two-dimensional (atomically thin) TMCs. We synthesized 47 compounds, including 32 binary compounds (based on the transition metals Ti, Zr, Hf, V, Nb, Ta, Mo, W, Re, Pt, Pd and Fe), 13 alloys (including 11 ternary, one quaternary and one quinary), and two heterostructured compounds. We elaborate how the salt decreases the melting point of the reactants and facilitates the formation of intermediate products, increasing the overall reaction rate. Most of the synthesized materials in our library are useful, as supported by evidence of superconductivity in our monolayer NbSe and MoTe samples and of high mobilities in MoS and ReS. Although the quality of some of the materials still requires development, our work opens up opportunities for studying the properties and potential application of a wide variety of two-dimensional TMCs.

2D Metal Chalcogenides for IR Photodetection

“…The growth methods and transfer technologies of 2DMCs are becoming more and more abundant, which make it more convenient to integrate with traditional 3D semiconductors to form heterostructures. The 3D semiconductors mainly include Si, GaAs, GaSb, etc.…”

A Facile and Effective Method for Patching Sulfur Vacancies of WS2 via Nitrogen Plasma Treatment

“…High‐performance transistors can be used in a variety of leading‐edge cross‐cutting fields, such as biosensors and artificial intelligence . The importance of obtaining high‐performance field‐effect transistors (FETs) motivates the search for new materials . Due to unique optoelectronic, electronic and chemical properties, transition metal dichalcogenides (TMDs) are attractive for use in the next‐generation high‐performance nanoelectronic era and substantial advancements in this field have been witnessed in the last several decades .…”

Anisotropic Growth and Scanning Tunneling Microscopy Identification of Ultrathin Even‐Layered PdSe2 Ribbons

“…By a MBE method, bilayer (2L) PdSe 2 islands were successfully synthesized on a conductive epitaxial graphene‐SiC(0001) substrate, showing a bandgap of 1.15 ± 0.07 eV by scanning tunneling microscopy/spectroscopy (STM/STS) . Moreover, the CVD synthesis of metallic TMDCs mainly depended on insulating substrates (such as SiO 2 /Si and quartz) . The growth mechanism at the 2D limit is still unclear, and onsite characterizations of the crystal quality (down to the atomic scale) and the thickness‐dependent band structure are extremely difficult.…”