Water-Assisted Concerted Layer Growth of T_d-Phase WTe₂ for Nonlinear Hall Effect and Microwave Rectification

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Tungsten ditelluride (WTe2) in its Td phase exhibits unique topological states and nonlinear transport properties.
• Scalable synthesis of high-quality, few-layer WTe2 with controlled layer numbers is a significant challenge.

Purpose of the Study:

• To develop a scalable synthesis method for deterministic growth of monolayer to trilayer Td-WTe2.
• To investigate the layer-dependent nonlinear transport properties of engineered Td-WTe2.

Main Methods:

• Water-assisted chemical vapor deposition (CVD) utilizing salt-assisted intermediates for precursor liquefaction.
• Vapor-liquid-solid (VLS) growth mechanism enabling tunable layer numbers.
• Transport measurements, including nonlinear Hall effect and microwave rectification, at varying temperatures.

Main Results:

• Deterministic growth of monolayer to trilayer Td-WTe2 with controlled flake size and density achieved.
• Trilayer WTe2 demonstrated significantly enhanced nonlinear Hall effect susceptibility compared to bilayers.
• Layer-dependent microwave rectification confirmed the influence of topological band structure and interlayer coupling.

Conclusions:

• The water-assisted CVD method provides precise layer control for Td-WTe2 synthesis.
• Engineered few-layer Td-WTe2 shows promise for advanced nonlinear quantum transport phenomena.
• These materials are suitable for next-generation high-frequency optoelectronic devices.