Charge density wave states in phase-engineered monolayer VTe₂

Abstract

Charge density wave (CDW) strongly affects the electronic properties of two-dimensional (2D) materials and can be tuned by phase engineering. Among 2D transitional metal dichalcogenides (TMDs), VTe 2 was predicted to require small energy for its phase transition and shows unexpected CDW states in its T-phase. However, the CDW state of H-VTe 2 has been barely reported. Here, we investigate the CDW states in monolayer (ML) H-VTe 2 , induced by phase-engineering from T-phase VTe 2 . The phase transition between T- and H-VTe 2 is revealed with x-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) measurements. For H-VTe 2 , scanning tunneling microscope (STM) and low-energy electron diffraction (LEED) results show a robust <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>2</mml:mn> <mml:msqrt> <mml:mn>3</mml:mn> </mml:msqrt> <mml:mo>×</mml:mo> <mml:mn>2</mml:mn> <mml:msqrt> <mml:mn>3</mml:mn> </mml:msqrt> </mml:mrow> </mml:math> CDW superlattice with a transition temperature above 450 K. Our findings provide a promising way for manipulating the CDWs in 2D materials and show great potential in its application of nanoelectronics.