Large-area and high-quality 2D transition metal telluride

TL;DR

This paper reports the successful large-scale synthesis of high-quality 2D transition metal tellurides using CVD, revealing novel structural and electronic properties, and enabling future quantum device applications.

Contribution

It introduces a controlled CVD method for large-area monolayer tellurides, overcoming previous low-yield methods and providing insights into their structural and electronic behaviors.

Findings

Achieved monolayer tellurides over 300 μm in size.

Discovered stacking boundary structures in bilayer WTe2.

Observed semimetal-insulator transition and enhanced superconductivity.

Abstract

Atomically thin transitional metal ditellurides like WTe2 and MoTe2 have triggered tremendous research interests because of their intrinsic nontrivial band structure. They are also predicted to be 2D topological insulators and type-II Weyl semimetals. However, most of the studies on ditelluride atomic layers so far rely on the low-yield and time-consuming mechanical exfoliation method. Direct synthesis of large-scale monolayer ditellurides has not yet been achieved. Here, using the chemical vapor deposition (CVD) method, we demonstrate controlled synthesis of high-quality and atom-thin tellurides with lateral size over 300 {\mu}m. We found that the as-grown WTe2 maintains two different stacking sequences in the bilayer, where the atomic structure of the stacking boundary is revealed by scanning transmission electron microscope (STEM). The low-temperature transport measurements revealed a novel semimetal-to-insulator transition in WTe2 layers and an enhanced superconductivity in few-layer MoTe2. This work paves the way to the synthesis of atom-thin tellurides and also quantum spin Hall devices.