Edge-Dominated Epitaxy of Topological Insulator Bi₂Se₃ with Ultrabroadband Response.

Abstract

Topological insulators, as a typical quantum state with robust spin-orbit coupling and topologically protected surface states, hold transformative potential for next-generation information devices. However, current fabrication approaches face critical limitations in thermodynamic uniformity and kinetic precision, hindering the scalable synthesis of high-quality crystals. Herein, we propose a flow-confined epitaxy strategy to synthesize large-scale Bi₂Se₃ topological insulators. Precisely regulating the chemical potential and reaction kinetics ensures atomic-level thermodynamic homogeneity and suppressed parasitic nucleation. The edge-dominated lateral diffusion mechanism enables the synthesis of millimeter-scale high-quality Bi₂Se₃ single crystals and 2-in. wafer-scale highly oriented Bi₂Se₃ crystals. Furthermore, through the construction of a 16 × 16 array, we demonstrate the ultrabroadband (520 nm-0.1 THz) and uniform response with excellent sensitivity of Bi₂Se₃ devices. This work presents a universal epitaxial paradigm for scalable topological insulator synthesis, which supports future integration into quantum photonic circuits and high-performance optoelectronic devices.