Simple Method to Obtain Large‐Size Single‐Crystalline Oxide Sheets

Synthetic techniques to prepare large-size, flexible, and high-quality single-crystalline sheets of transition metal oxides are crucial to developing low-energy consumption devices. One promising way is a lift-off and transfer technique using a heterostructure of polymer supporting oxide and Sr3Al2O6 (SAO) layers grown on a single-crystalline substrate. By removing the water-soluble SAO and the supporting layers, the oxide sheet is obtained. Although some ferroelectric flexible sheets are prepared by this method, a simpler method for obtaining large-size sheets is required. Herein, a lift-off and transfer method is proposed without a supporting layer. With this simple method, single-crystalline SrRuO3 and BaTiO3 flexible sheets with a lateral size of a few millimeters are successfully prepared. The SrRuO3 sheet exhibits high crystallinity and conductivity. Meanwhile, the ferroelectricity of the BaTiO3 sheet is successfully observed via polarization hysteresis loop measurements. In addition to the simplicity, this method has low costs and the substrate is reusable. Accordingly, the proposed method could enhance the development of various kinds of large-size functional oxide sheets.