Super-tetragonal Sr 4 Al 2 O 7 as a sacrificial layer for high-integrity freestanding oxide membranes

• DOI: 10.1126/science.adi6620
• Publication Date: 2024-01-25T18:58:30Z
• Authors: Jinfeng Zhang; Ting Lin; Ao Wang; Xiaochao Wang; Qingyu He; Huan Ye; Jingdi Lu; Qing Wang; Zhengguo Liang; Feng Jin; Shengru Chen; Minghui Fan; Er-Jia Guo; Qinghua Zhang; Lin Gu; Zhenlin Luo; Liang Si; Wenbin Wu; Lingfei Wang
• Keywords: 0301 basic medicine; 03 medical and health sciences

Identifying a suitable water-soluble sacrificial layer is crucial to fabricating large-scale freestanding oxide membranes, which offer attractive functionalities and integrations with advanced semiconductor technologies. Here, we introduce a water-soluble sacrificial layer, “super-tetragonal” Sr 4 Al 2 O 7 (SAO T ). The low-symmetric crystal structure enables a superior capability to sustain epitaxial strain, allowing for broad tunability in lattice constants. The resultant structural coherency and defect-free interface in perovskite ABO 3 /SAO T heterostructures effectively restrain crack formation during the water release of freestanding oxide membranes. For a variety of nonferroelectric oxide membranes, the crack-free areas can span up to a millimeter in scale. This compelling feature, combined with the inherent high water solubility, makes SAO T a versatile and feasible sacrificial layer for producing high-quality freestanding oxide membranes, thereby boosting their potential for innovative device applications.