Atomic-Scale Chemical Conversion of Single-Layer Transition Metal Dichalcogenides.
basic_science · Level V
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- Record sourced from PubMed, PMID 30987421.
- Also identified by DOI 10.1021/acsnano.9b00756.
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Abstract
Chemical conversion by atomic substitution offers a powerful route toward the creation of unusual structures and functionalities. Here, we demonstrate the progressive transformation of single-layer TiTe<sub>2</sub> into TiSe<sub>2</sub> by reaction with a Se flux in vacuum. Angle-resolved photoemission spectroscopy and scanning tunneling microscopy reveal intriguing reaction patterns involving TiSe<sub>2</sub> island ingrowth starting from the TiTe<sub>2</sub> island edges, while the band structure and core level signatures of TiSe<sub>2</sub> grow in intensity at the expense of those corresponding to TiTe<sub>2</sub>. Lattice mismatch between TiTe<sub>2</sub> and TiSe<sub>2</sub> results in misfit holes and lattice distortions over a distance behind a seamless fingerlike reaction front. The regions of TiSe<sub>2</sub> and TiTe<sub>2</sub> are distinguished by a height difference and a charge density wave (CDW) at different transition temperatures. The method of in situ chemical conversion offers opportunities for atomic-scale engineering of layered transition metal dichalcogenides that host useful properties arising from CDW, Dirac, Weyl, superconducting, spin-valley, and magnetic structures.