Controlled epitaxy and patterned growth of one-dimensional crystals via surface treatment of two-dimensional templates

Mixed-dimensional van der Waals (vdW) heterostructures offer promising platforms for exploring interesting phenomena and functionalities. To exploit their full potential, precise epitaxial processes and well-defined heterointerfaces between different components are essential. Here, we control the growth of one-dimensional (1D) vdW microwires on hexagonal crystals via plasma treatment of the growth templates. AgCN serves as a model 1D system for examining the dependence of the nucleation and growth parameters on the surface treatment conditions and substrate types. The oxygen-plasma-treated transition metal dichalcogenides form step edges mediated by formation of surface metal oxides, leading to robust AgCN epitaxy with an enhanced nucleation density and low horizontal growth rates. Monte Carlo simulations reproduce the experimentally observed growth behaviors and unveil the crucial growth parameters, such as surface diffusivity. The plasma treatment results in distinct effects on graphite and hexagonal boron nitride templates, which undergo plasma-induced amorphization and deactivation of the AgCN vdW epitaxy. We achieve the selective growth of AgCN microwires on graphite using the deactivated vdW epitaxy. This study offers significant insights into the impact of surface treatment on 1D vdW epitaxy, opening avenues for controlled fabrication of mixed-dimensional vdW heterostructures.