Super-tetragonal Sr<sub>4</sub>Al<sub>2</sub>O<sub>7</sub> as a sacrificial layer for high-integrity freestanding oxide membranes.
basic_science · Level V
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- Record sourced from PubMed, PMID 38271502.
- Also identified by DOI 10.1126/science.adi6620.
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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" Sr<sub>4</sub>Al<sub>2</sub>O<sub>7</sub> (SAO<sub>T</sub>). 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<sub>3</sub>/SAO<sub>T</sub> 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<sub>T</sub> a versatile and feasible sacrificial layer for producing high-quality freestanding oxide membranes, thereby boosting their potential for innovative device applications.