Preparation and Ferroelectric Properties of Freestanding BaTiO₃ Thin Films

BaTiO₃ (BTO) ferroelectric oxide thin films have attracted extensive attention due to their potential applications in non-volatile information storage, intelligent sensing, biomedicine, nanogenerators and other fields. At present, in order to ensure the high-quality epitaxial growth of BTO thin films, lattice-matched oxides are usually selected as substrates, and there is a strong chemical bond between the grown thin film and the substrate, which is difficult to peel it off from the substrate, so it cannot be transferred to the Si substrate that can be used for high-density device integration. In this paper, the BTO epitaxial thin film grown on Nb-SrTiO₃ (Nb-STO) substrate is transferred to Si substrate without folds by using water-soluble Sr₃Al₂O₆ (SAO) as a sacrificial layer. Moreover, the freestanding thin films still maintain perfect crystallinity and room-temperature ferroelectric properties. This conclusion establishes a certain foundation for the use of freestanding oxide thin films in the integration of high-density ferroelectric devices.