A Flux Model-Driven Transverse-Oriented Growth Strategy for the Synthesis of Large-Area Two-Dimensional Molybdenum-Based Materials

Abstract

Mechanical exfoliation of thin sheets remains a prevalent technique for acquiring high-quality two-dimensional (2D) materials, as the chemical vapor deposition (CVD) technique for 2D transition metal dichalcogenides (TMDs) compounds lacks unambiguous theoretical guidance, complicating the precise control of material growth and the synthesis of the desired area and mass. In this paper, we establish the theoretical foundation of the vapor–liquid–solid (VLS) in CVD method growth of TMDs, i.e., the flux model, supported by theoretical analysis and experimental data. Utilizing this theoretical insight, this study proposes a nonvolatile molten salt flux-dominated VLS growth strategy. The introduction of potassium trimolybdate (K₂Mo₃O₁₀) as a stable molten salt medium enabled the cross-system controlled synthesis of molybdenum-based compounds (MoS₂, MoSe₂, MoO₂, Mo₃Te₄) by overcoming the reliance of the traditional VLS approach on volatile precursors. The low volatility of this molten salt flux and the synergistic diffusion effect of alkali metals markedly reduced nucleation density and facilitated the targeted lateral growth of atoms, resulting in the successful preparation of millimeter-sized single crystals (maximum size of 918 μm) and centimeter-sized continuous films. The MoS₂ films from this demonstrate exceptional electrical performance (mobility 21.74 cm² V^–1 s^–1, switching ratio ∼10⁵) in back-gated field-effect transistors with enhanced process compatibility. This study introduces a novel approach for the controllable synthesis of 2D semiconductors using molten salt flux engineering, with its cross-material applicability and centimeter-scale production capabilities establishing a basis for the sustainable manufacturing of wafer-scale electronic devices.