van der Waals Epitaxial Growth of Atomically Thin 2D Metals on Dangling‐Bond‐Free WSe₂ and WS₂

TLDR

2D metals exhibit unique properties such as charge density waves, magnetism, and superconductivity, yet synthesizing monolayer‑thick nanosheets remains a significant challenge. By employing dangling‑bond‑free WSe₂ or WS₂ as van der Waals epitaxy substrates, the authors successfully grew atomically thin MTe₂ (M = V, Nb, Ta) monolayers and vertical heterojunctions, demonstrating that these epitaxial metals serve as low‑damage contacts for 2D semiconductors and establishing a robust pathway for ultrathin 2D metal synthesis.

Abstract

Abstract 2D metals have attracted considerable recent attention for their special physical properties, such as charge density waves, magnetism, and superconductivity. However, despite some recent efforts, the synthesis of ultrathin 2D metals nanosheets down to monolayer thickness remains a significant challenge. Herein, by using atomically flat 2D WSe 2 or WS 2 as the growth substrate, the synthesis of atomically thin 2D metallic MTe 2 (M = V, Nb, Ta) single crystals with the thickness down to the monolayer regime and the creation of atomically thin MTe 2 /WSe 2 (WS 2 ) vertical heterojunctions is reported. Comparison with the growth on the SiO 2 /Si substrate under the same conditions reveals that the utilization of the dangling‐bond‐free WSe 2 or WS 2 as the van der Waals epitaxy substrates is crucial for the successful realization of atomically thin MTe 2 (M = V, Nb, Ta) nanosheets. It is further shown that the epitaxial grown 2D metals can function as van der Waals contacts for 2D semiconductors with little interface damage and improved electronic performance. This study defines a robust van der Waals epitaxy pathway to ultrathin 2D metals, which is essential for fundamental studies and potential technological applications of this new class of materials at the 2D limit.