Atomics sawtooth-like metal films for vdW-layered single-crystal growth

Hayoung Ko
Sungkyunkwan University, Suwon, Republic of Korea _______________________________________

Two-dimensional (2D) vdW layered materials have showcased remarkable physical and chemical properties [1]. However, to harness these intrinsic properties optimally, the large-scale production of single-crystal (SC) 2D films is essential. While many researchers have successfully grown large-scale SC 2D films on various SC substrates but these methods often come at a high cost, demand extended processing times, or involve intricate techniques [2-4]. Recognizing this challenge, we introduce a melting and solidification (MS) method for growing SC films on polycrystalline substrates—a method that is both cost-effective and time-efficient compared to existing techniques. we delve deeper to uncover the mechanism behind the formation of SC metal films using this MS process. Our molecular dynamics simulations offer an understanding of the energetic dynamics at play between metal layers and their substrates. Our findings shed light on how the solidification of metals, beginning at high-index W facets with higher interface energy, progresses to areas with lower energy, ultimately leading to the emergence of SC metal films. Further, we demonstrated the growth of the representative SC hBN films on AS SC Cu films, highlighting its potential in oxygen barrier applications.

Figure. Large-scale single-crystal (SC) atomic sawtooth (AS) metal film on polycrystalline (PC) substrates. a, Schematic representation of the melting–solidification (MS) process used to form AS metal films on PC W foils. The insets in (a) show photographs of Cu substrates before and after the MS process. b-d, Electron backscatter diffraction (EBSD) images of b) annealed PC W foil, c, Cu foil,and d, SC AS Cu film, with an inverse pole figure (IPF) map. e,f, Representative scanning electron microscopy (SEM) images of SC AS Cu and Cu (111). g, Cross-sectional annular dark-field scanning transmission electron microscopy image of SC AS Cu film.

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