Electrical properties of single-crystalline WTe2 nanobelts grown from eutectic alloy reservoir

Abstract

Among diverse transition metal dichalcogenide compounds, semimetallic tungsten ditelluride (WTe2) in the distorted 1T phase has received renewed attention from the experimental observations of non-saturating large magnetroresistance and high mobility, and from the theoretical prediction of large-gap quantum spin Hall insulator. However, the production of high-quality WTe2 layers remains an unsolved challenge mainly due to the low environmental stability and activity of Te, and difficulties in Te incorportation during growth. In this study, we have obtained single-crystalline one-dimensional (1D) WTe2 nanobelts at low temperatures (T ~500 °C) in large scale via the use of Te-rich eutectic metal alloys (e.g., CuxTey). The as-synthesized WTe2 samples exhibit a distinct 1D belt-like morphology with layered cross-section of <12.2 ± 6.6 nm in thickness. The introduction of Te-rich eutectic metal alloys as a Te reservoir eliminates the Te deficiency in the resulting products and the contamination by impurities encountered with chemical vapor deposition. As a result, the resulting 1D products are highly pure, stoichiometric, structurally uniform, and free of defects, resulting in high electrical performances. All tested WTe2 nanobelt devices showed low resistances (ρ < 1 mΩ cm), close to that of the mechanically exfoliated ones by the order of magnitude [1]. Furthermore, they showed a remarkably high breakdown current density (JB) of up to ~94 MA/cm2, promising their future device applications as a downscaled interconnect. We believe that this approach may be used as a general strategy for fabricating 1D layered nanostructures and truly exciting opportunity that can lead to dozens of new 1D nanomaterials of electronic quality, which may offer unique properties that are not available in other materials.