High dielectric tunability in ferroelectric-paraelectric bilayers and multilayer superlattices

The dielectric tunability of ferroelectric/paraelectric bilayers and multilayer superlattices are examined theoretically. A numerical analysis is carried out for a pseudomorphic (001) BaTiO3∕SrTiO3 heteroepitaxial bilayer on (001) SrTiO3 and a stress-free BaTiO3∕SrTiO3 bilayer. We show that these structures are capable of tunabilities greater than 90% due to electrostatic and electromechanical coupling between layers. Moreover, we develop the methodology for incorporation conventional integrated circuit silicon dielectrics into heteroepitaxial structures that can reduce current leakage while maintaining high tunability, thereby enabling the device designer flexibility toward the optimization of microwave and millimeter wave elements.