K⁺-free mica-assisted epitaxy of Bi-based chalcogenide and oxychalcogenide single-crystals.

Abstract

A material family that intrinsically hosts topological, high-mobility semiconducting and ferroelectric properties offers a platform for exploring new physical phenomena and advancing next-generation electronics and optoelectronics. Bismuth-based chalcogenides and oxychalcogenides are especially promising in this context due to their compositionally tunable functionalities. However, their development is hindered by the lack of a general, scalable synthesis method, as existing approaches are material-specific and rely on costly, lattice-matched substrates. Here, we report a synergistic epitaxy strategy that pairs elemental precursors with an atomically engineered K⁺-free mica surface, enabling universal growth of nine millimeter-sized bismuth-based chalcogenide and oxychalcogenide single crystals, including topological insulators, high-mobility semiconductors, and ferroelectrics/dielectrics. High-quality materials enable high-performance transistors and broadband photodetectors with high responsivities. Furthermore, we demonstrate their integration into large-scale, uniform arrays and showcase their imaging capabilities across visible to infrared bands. This work establishes a scalable and material-agnostic synthesis framework, unlocking the systematic exploration and device integration of this multifunctional material family.