Van der Waals template-encoded soft epitaxy of tellurium enabled by atomic layer deposition.

Abstract

Van der Waals (vdW) epitaxy can integrate lattice-mismatched crystals with atomically sharp, pristine interfaces. However, translating this concept to atomic layer deposition (ALD), a standard for low-temperature, layer-by-layer growth, remains challenging because precursors adsorb transiently on chemically inert vdW basal planes, leading to physisorption-limited nucleation and poor crystalline ordering. Here, we introduce diffusion-steered epitaxial ALD (Epi-ALD), redefining vdW surfaces as programmable kinetic-thermodynamic landscapes and demonstrate highly crystalline tellurium at 150°C. Epi-ALD couples surface-potential-encoded physisorption with long-range diffusion to promote ordered nucleation and epitaxial alignment. This "soft" pathway enables strain-free tellurium epitaxy with a pristine vdW gap (∼1.4 angstrom) despite lattice mismatch (>3.6%) and generalizes across multiple vdW templates. Retaining hallmark advantages of ALD including scalability and uniformity, we further program in-plane orientation through vdW symmetry engineering to achieve quasi-single-crystalline tellurium films with pronounced anisotropy and a chiral anomaly signature. Our work establishes a universal, low-thermal-budget approach for integrating vdW materials and expands the scope of epitaxy within the ALD paradigm.