Water-Assisted Concerted Layer Growth of T<sub>d</sub>-Phase WTe<sub>2</sub> for Nonlinear Hall Effect and Microwave Rectification.

Wu, Shuang; Liu, Yu-Fei; Kwon, Sun Yong; Lim, Ting Yong; Yeom, Sinchul; Gao, Anyuan; Li, Houchen; Unocic, Raymond R et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

The T<sub>d</sub> phase of tungsten ditelluride (WTe<sub>2</sub>), a noncentrosymmetric transition metal dichalcogenide, hosts rich correlated phenomena, topological states, and nonlinear transport responses. However, the scalable synthesis of high-quality few-layer WTe<sub>2</sub> with precise layer control remains challenging. Here, we report a water-assisted chemical vapor deposition approach that deterministically grows monolayer to trilayer T<sub>d</sub>-WTe<sub>2</sub> with controlled flake size and density. Moisture-mediated precursor liquefaction through salt-assisted intermediates enables vapor-liquid-solid growth and tunable layer numbers through a concerted layer growth mode. Transport studies reveal that trilayer WTe<sub>2</sub> exhibits a nonlinear Hall effect susceptibility of 1.1 μm·V<sup>-1</sup> at 10 K and 0.5 μm·V<sup>-1</sup> at 50 K, nearly an order of magnitude higher than that in bilayers, consistent with the calculated Berry curvature dipole enhancement. Layer-dependent microwave rectification further highlights the influence of topological band structure and interlayer coupling. These results establish layer-engineered T<sub>d</sub>-WTe<sub>2</sub> as a promising platform for nonlinear quantum transport and high-frequency optoelectronic applications.