2026-06-08 ノースカロライナ州立大学（NC State）
＜関連情報＞
- https://news.ncsu.edu/2026/06/van-der-waals-forces-thin-films/
- https://pubs.acs.org/doi/10.1021/acsnano.6c02795
数層強誘電体スズモノカルコゲナイドにおける厚さ、歪み、およびドメイン構造のヘテロエピタキシャル制御 Heteroepitaxial Control of Thickness, Strain, and Domain Architecture in Few-Layer Ferroelectric Tin Monochalcogenides
Yueyin Wang,Garrett Baucom,Pochun Hsieh,Tao Zhou,Tugba Isik,Haoye Sun,Hana Jones,David Szympruch,Albert Suceava,Reza Ghanbari,Yusen Pei,Guanyue Chen,Rui Liu,Franky So,Dali Sun,Ruijuan Xu,Venkatraman Gopalan,Honggyu Kim,and Yin Liu
ACS Nano Published: June 3, 2026
DOI:https://doi.org/10.1021/acsnano.6c02795
Abstract
Thin-film epitaxy and epitaxial strain have been widely exploited to tune domain configurations, switching behavior, and ferroic properties in conventional three-dimensional ferroelectric thin films; however, its application to controlling the properties of two-dimensional (2D) ferroelectrics has remained largely unexplored. Here, using SnX (X = Se, S) as a model system, we demonstrate heteroepitaxial control of thickness, strain state, and domain architecture in few-layer ferroelectric SnX via growth on monolayer MoS2 van der Waals (vdW) templates. Compared with conventional growth, MoS2-templated heteroepitaxy promotes epitaxial alignment, yielding ultrathin SnSe films with improved crystalline quality, full areal coverage, and enlarged lateral dimensions. Strong interfacial epitaxial coupling induces pronounced in-plane strain and stabilizes a hierarchical ferroelastic domain architecture, in which long-range 90° stripe domains are further subdivided into nanoscale rotational variants, as revealed by scanning transmission electron microscopy and synchrotron X-ray microscopy. Piezoresponse force microscopy and second-harmonic polarimetry confirm robust in-plane polarization, while ferroelectricity in SnSe is established through polarization-electric field hysteresis and nonvolatile ferroelectric resistive switching with on/off ratios approaching 1000. A nonvolatile, switchable ferroelectric diode effect further evidences direct coupling between polarization and charge transport. Notably, ferroelectric switchability exhibits a strong thickness dependence and is preserved only below ∼10 layers. This vdW heteroepitaxial strategy is further extended to ferroelectric SnS. The seamless heteroepitaxial integration of 2D ferroelectrics with CMOS-compatible, wafer-scale MoS2 templates provides a general and scalable route for strain-enabled structural and ferroelectric engineering in emerging memory and low-power optoelectronic applications.
