Researchers develop novel ‘super-tetragonal’ sacrificial layer for freestanding oxide membranes

Researchers have developed a brand new water-soluble sacrificial layer, “super-tectragonal” Sr₄Al₂O₇ (SAO_T), with broad tunability in lattice constants, which can be utilized to arrange high-quality freestanding oxide membrane. Their work is printed in Science.

A freestanding oxide membrane is a sort of low-dimensional quantum materials that maintains single-crystal properties even after eradicating the substrate, possessing each the coupled properties of multi-degree-of-freedom in correlated electron programs and the structural flexibility of two-dimensional supplies. Its distinctive properties like superelasticity provide the potential to induce novel quantum-derived phenomena and develop ultrathin versatile digital gadgets.

Nonetheless, the misfit pressure leisure between the water-soluble sacrificial layer and the oxide membrane triggers the formation of high-density cracks through the water-assisted exfoliation of the freestanding oxide membrane, compromising the crystallinity and integrity of the present freestanding oxide membrane. How one can suppress the crack formation and procure large-area, extremely crystalline freestanding oxide membranes stays a problem.

To deal with the issue, the workforce delved into the pulsed laser deposition progress window of Sr-Al-O (SAO) primarily based water-soluble sacrificial layer and found a beforehand unknown Sr₄Al₂O₇ movie, which displays extraordinary properties.

The biaxial-strained Sr₄Al₂O₇ movie has a tetragonal structural symmetry, enabling coherent progress of high-quality ABO₃/SAO_T epitaxial heterostructures, which suppresses the crack formation throughout water-assisted launch and thus enhancing the crystallinity and integrity of freestanding oxide membrane.

The workforce additionally verified the exfoliation impact of perovskite oxide movies with a broad lattice fixed vary (3.85 to 4.04 Å) and revealed that the crack-free areas of the freestanding oxide membrane launched from the Sr₄Al₂O₇ sacrificial layer can span up to some millimeters in scale, which is 1–3 orders of magnitude bigger than earlier freestanding oxide membrane. As well as, the crystallinity and functionalities of the workforce’s freestanding oxide membrane are akin to the epitaxial membranes grown on single crystalline substrates.

Moreover, the workforce found that the distinctive construction of Sr₄Al₂O₇ ends in excessive water solubility, considerably lowering the time of water-assisted releasing processes and enhancing the effectivity of freestanding oxide membrane.

This discovery is a breakthrough in bettering the integrity and crystallinity of freestanding oxide membranes, which might improve their software potential in low-dimensional versatile digital gadgets. Reviewers extremely commend this work, saying that “(this work) has the potential to have a broad influence on oxide electronics from a number of views.”

The analysis workforce was led by Prof. Wu Wenbing and Prof. Wang Linfei from the College of Science and Expertise of China, in collaboration with Prof. Si Liang’ s workforce from Northwest College.