Vanadium‐Assisted Epitaxy Growth of Wafer‐Scale Bilayer Tungsten Disulfide Ferroelectric Semiconductor Single Crystals with High‐Endurance Memory

Abstract

Abstract Bilayer rhombohedral‐stacked (3R) transition metal dichalcogenides (TMDCs) with switchable polarization expand the ferroelectric scope and provide a promising avenue to construct low‐power and nonvolatile memory devices. However, epitaxy growth of wafer‐scale 2D ferroelectric semiconductor single crystals is still on the way due to the challenge of phase structure and domain orientation control. Here, a vanadium‐assisted epitaxy strategy is designed to synthesize two‐inch bilayer 3R‐WS 2 single crystals on c ‐plane sapphire. The introduction of vanadium not only increases the interlayer coupling to break the formation energy degeneracy between 3R‐ and hexagonal‐stacked (2H) WS 2 , but also promotes the parallel steps evolution on sapphire surfaces to induce the unidirectional bilayer domains nucleation. Ferroelectric semiconductor field‐effect transistors with high endurance (more than 10 5 cycles) and a large write/erase ratio (3.0 × 10 5 ) are fabricated due to excellent polarization. This work represents a substantial leap in terms of controlling synthesis and memory device construction of wafer‐scale 2D ferroelectric semiconductor single crystals, which should promote the further design of logic‐in‐memory chips to overcome von Neumann architecture bottlenecks.