Microstructure control and property switching in stress-free van der Waals epitaxial VO2 films on mica
Microstructure control and property switching in stress-free van der Waals epitaxial VO2 films on mica
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DOI：
10.1016/j.matdes.2023.111864
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发表时间：
2023-04-03
影响因子：
8.4
通讯作者：
Eklund，Per
中科院分区：
文献类型：
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作者：
Ekstrom，Erik;Hurand，Simon;Eklund，Per
在弱键合衬底上实现无应力无机外延膜对于需要膜转移到不进行晶种外延的表面上的应用是重要的。通常通过利用天然的货车德瓦尔斯层（例如，石墨烯），但这在非层状材料中难以实现。在这里，我们展示了货车德瓦尔斯外延的无应力薄膜的非层状材料VO 2云母。薄膜表现出面外010织构，具有三个面内取向，继承自衬底的晶畴。晶格参数与薄膜厚度不变，表明弱膜基结合和完整的界面应力松弛。的平面外的域的大小与膜的厚度单调缩放，但在平面内域的大小表现出最小值，这表明大的平面内域的成核支持随后的岛的生长。互补的从头算研究表明，VO 2成核和货车德瓦尔斯外延涉及微妙的极化效应，周围，并积极参与，表面钾原子的云母表面。VO 2薄膜表现出窄畴尺寸敏感的电导-温度滞回特性。这些结果为通过微结构控制来调节非层状材料如VO 2的无应力货车范德华外延膜的性能提供了希望。
Realizing stress-free inorganic epitaxial films on weakly bonding substrates is of importance for applications that require film transfer onto surfaces that do not seed epitaxy. Film-substrate bonding is usually weakened by harnessing natural van der Waals layers (e.g., graphene) on substrate surfaces, but this is difficult to achieve in non-layered materials. Here, we demonstrate van der Waals epitaxy of stress-free films of a non-layered material VO2on mica. The films exhibit out-of-plane 010 texture with three in-plane orientations inherited from the crystallographic domains of the substrate. The lattice parameters are invariant with film thickness, indicating weak film-substrate bonding and complete interfacial stress relaxation. The out-of-plane domain size scales monotonically with film thickness, but the in-plane domain size exhibits a minimum, indicating that the nucleation of large in-plane domains supports subsequent island growth. Complementaryab initioinvestigations suggest that VO2nucleation and van der Waals epitaxy involves subtle polarization effects around, and the active participation of, surface potassium atoms on the mica surface. The VO2films show a narrow domain-size-sensitive electrical-conductivity-temperature hysteresis. These results offer promise for tuning the properties of stress-free van der Waals epitaxial films of non-layered materials such as VO2through microstructure control.