Cai Yu, Xu Ya-Ting, Fu Meng-Yao, Feng Min, Peng Huai-Yu, Jiang Ya-Fei, Wang Bo-Wen, Wang Ya-Qiong, Guan Zhao, Chen Bin-Bin, Zhong Ni, Duan Chun-Gang, Xiang Ping-Hua
Key Laboratory of Polar Materials and Devices (Ministry of Education), Shanghai Center of Brain-inspired Intelligent Materials and Devices, Department of Electronics, East China Normal University, Shanghai 200241, China.
Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, Shanxi, China.
ACS Appl Mater Interfaces. 2025 Apr 9;17(14):21459-21468. doi: 10.1021/acsami.5c01102. Epub 2025 Mar 26.
Freestanding perovskite oxide films possess extra features of structural tunability and stacking ability when exfoliated from rigid substrates, providing potential applications in silicon-based semiconductors and flexible electronics. Well epitaxial growth on sacrificial layers is crucial to preserve fascinating physical properties in freestanding oxide membranes. However, the weak strain adaptability of sacrificial layers limits their coherent epitaxial growth on different substrates. Here, we demonstrate a simple perovskite sacrificial layer of SrMnO (SMO) with superior strain adaptability, capable of being epitaxially grown on an ultrabroad spectrum of substrates with lattice constants ranging from 3.715 Å to 3.946 Å. An atomically flat SMO has been employed to synthesize diverse crack-free freestanding single-crystal perovskite oxides on a millimeter scale. The SMO sacrificial layer exhibits a high dissolution rate of 3.1 mm/min. LaAlO (LAO), SrTiO (STO), SrRuO (SRO), and BiFeO (BFO) are typical examples and are transferred intact to silicon wafers or flexible substrates. The intrinsic ferromagnetic and ferroelectric properties are well-maintained in freestanding SRO and BFO membranes, respectively. Freestanding STO and LAO membranes can serve as transferable heteroepitaxy surfaces for perovskite oxide films, which is demonstrated by the coherent epitaxial growth of the widely used ferromagnetic LaSrMnO films with a different strain state. Superior strain adaptability and ultrafast dissolution rate make SMO a prevailing sacrificial layer for synthesizing high-quality freestanding perovskite oxides with a wider range of lattice parameters.
独立的钙钛矿氧化物薄膜从刚性衬底上剥离时具有结构可调性和堆叠能力等额外特性，在硅基半导体和柔性电子学中具有潜在应用。在牺牲层上实现良好的外延生长对于保持独立氧化物薄膜中引人入胜的物理性质至关重要。然而，牺牲层的应变适应性较弱限制了它们在不同衬底上的相干外延生长。在此，我们展示了一种具有优异应变适应性的简单钙钛矿牺牲层SrMnO（SMO），它能够在晶格常数范围从3.715 Å到3.946 Å的超宽谱衬底上外延生长。已采用原子级平整的SMO在毫米尺度上合成了多种无裂纹的独立单晶钙钛矿氧化物。SMO牺牲层表现出3.1毫米/分钟的高溶解速率。LaAlO（LAO）, SrTiO（STO）, SrRuO（SRO）和BiFeO（BFO）是典型例子，它们被完整转移到硅片或柔性衬底上。独立的SRO和BFO薄膜分别很好地保持了其本征铁磁和铁电性能。独立的STO和LAO薄膜可作为钙钛矿氧化物薄膜的可转移异质外延表面，这通过具有不同应变状态的广泛使用的铁磁LaSrMnO薄膜的相干外延生长得到证明。优异的应变适应性和超快溶解速率使SMO成为合成具有更广泛晶格参数的高质量独立钙钛矿氧化物的主流牺牲层。
