The field effect in a metal–ferroelectric–semiconductor system of multilayer ferroelectric films with various structure types

The ability to grow the interfacial defect-poor Sr$_{0.5}$Ba$_{0.5}$Nb$_{2}$O$_{6}$+Ba$_{0.2}$Sr$_{0.8}$TiO$_{3}$ and Ba$_{0.8}$Sr$_{0.2}$TiO$_{3}$+Ba$_{0.4}$Sr$_{0.6}$TiO$_{3}$ ferroelectric films onto the doped silicon substrates is discussed. A study of piezo-response via the quasi-static method (using the electrode area of 0.07 mm$^2$) reveals that heterostructures possess an initial polarized ferroelectric state with a spontaneous polarization vector perpendicular to the substrate at any type of Si conductivity. The polarized state is established to refer to two-dimension stresses in the ferroelectric, which is tunable through a preprepared Ba$_{x}$Sr$_{1-x}$TiO$_{3}$ onto a sublayer substrate as well as to a thickness of this sublayer. Polarization switching in Sr$_{0.5}$Ba$_{0.5}$Nb$_{2}$O$_{6}$/Si and Ba$_{0.8}$Sr$_{0.2}$TiO$_{3}$/Si heterostructures under the external field arises at only using the barium–strontium titanate sublayer predeposited onto silicon. A 15% decrease in switching polarization in Ba$_{0.8}$Sr$_{0.2}$TiO$_{3}$/Ba$_{0.4}$Sr$_{0.6}$TiO$_{3}$/Si structures is observed after 500 h.