Tailored Vapor Deposition Unlocks Large-Grain, Wafer-Scale Epitaxial Growth of 2D Magnetic CrCl₃.

Abstract

Two-dimensional magnetic materials (2D-MM) are an exciting playground for fundamental research, and for spintronics and quantum sensing. However, their large-grain, wafer-scale synthesis using scalable vapor deposition methods is still an unsolved challenge. Here, a tailored physical vapor transport deposition (PVTD) method is developed, which enables centimeter-scale, epitaxial growth of semiconducting 2D-MM CrCl₃ at 500°C (on mica substrate). A controlled synthesis protocol, enabled via four process innovations, (i) low emissivity secondary heating source, (ii) very-high carrier-gas flow, (iii) dynamic precursor flux control, and (iv) oxygen/moisture removal, suppresses redox etching and drives growth beyond the diffusion limit for wafer-scale growth. Optical, stoichiometric, structural, and magnetic characterization confirm single-crystalline, phase-pure 2D-MM CrCl₃. Substrate temperature tunes thickness of films from few-layers to tens of nanometers, while flow rate controls nucleation density and coverage. Further, we demonstrate selective-area growth and large-area transfer, validating potential wafer-level device integration. Substrate-dependent growth features are explained using density functional theory and state-of-the-art machine learning interatomic potential-based atomic-scale simulations. This scalable, flexible vapor deposition approach offers a general route for synthesizing several (volatile and reactive) 2D-MM and bridges the scalability gap from conventional wafer-scale materials. The low-temperature growth will enable the creation of hybrid functional heterostructures.