Super-tetragonal Sr4Al2O7 as a sacrificial layer for high-integrity freestanding oxide membranes

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

doi:10.1126/science.adi6620

Super-tetragonal Sr₄Al₂O₇ as a sacrificial layer for high-integrity freestanding oxide membranes

Science. 2024 Jan 26;383(6681):388-394. doi: 10.1126/science.adi6620. Epub 2024 Jan 25.

Authors

Jinfeng Zhang^#¹, Ting Lin^#², Ao Wang^#¹, Xiaochao Wang^#³, Qingyu He⁴, Huan Ye¹, Jingdi Lu¹, Qing Wang¹, Zhengguo Liang¹, Feng Jin¹, Shengru Chen², Minghui Fan¹, Er-Jia Guo², Qinghua Zhang², Lin Gu⁵, Zhenlin Luo⁴, Liang Si^{3

6}, Wenbin Wu^{1

7

8}, Lingfei Wang¹

Affiliations

¹ Hefei National Research Center for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China.
² Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
³ School of Physics, Northwest University, Xi'an 710127, China.
⁴ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, China.
⁵ Beijing National Center for Electron Microscopy and Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
⁶ Institut für Festkörperphysik, TU Wien, 1040 Vienna, Austria.
⁷ Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China.
⁸ Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.

^# Contributed equally.

PMID: 38271502
DOI: 10.1126/science.adi6620

Abstract

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" Sr₄Al₂O₇ (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 ABO₃/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.