Charge Density Wave Phase Transitions in Large-Scale Few-Layer 1T-VTe2 Grown by Molecular Beam Epitaxy

Charge density wave (CDW) as a novel effect in two-dimensional transition metal dichalcogenides (TMDs) has obtained a rapid rise of interest for the physical nature and potential applications in oscillator and memory devices. Here, we report var der Waals epitaxial growth of centimeter scale 1T-VTe2 thin films on mica by molecular beam epitaxy. The VTe2 thin films showed sudden resistance change at temperature of 240 K and 135 K, corresponding to two CDW phase transitions driven by temperature. Moreover, the phase transitions can be driven by electric field due to local Joule heating and the corresponding resistance states are nonvolatile and controllable, which could be applied to the memory device where the logic states can be switched by electric field. The multistage CDW phase transitions in the VTe2 thin films could be contributed to electron–phonon coupling in the two-dimensional VTe2, which is supported by twice pronounced Raman blue shifts of the vibration modes associating with in-plane phonons a...