Chemical Vapor Deposition of 2D Vanadium Disulfide and Diselenide and Raman Characterization of the Phase Transitions

Abstract 2D metallic vanadium dichalcogenides (VX 2 ) have renewed interest due to their unique physical properties and potential applications as high‐performance functional nanomaterials. Herein, the synthesis and phase transitions of 2D metallic VX 2 are investigated. The synthesis is done by chemical vapor deposition using hexagonal boron nitride and mica as substrates. High‐quality VX 2 flakes with sub‐10 nm thickness are obtained and characterized by transmission electron microscopy. Temperature‐dependent Raman characterization between 330 and 5 K is conducted and remarkable changes of Raman modes at around 150 K for VS 2 flakes and 110 K for VSe 2 flakes are revealed, indicating charge density wave phase transitions. Temperature‐dependent electrical measurements have also supported the phase transitions observed in Raman characterization.