Nonlinear Dielectric Bahaviour of Metal/Ferroelectric/Metal and Metal/Ferroelectric/Semiconductor-Heterostructures

The influence of size effects and of the microstructure of interfaces and thin films on the linear properties of ferroelectrics is presently a widely studied topic world-wide. However, their influence on nonlinear properties of nanoscaled ferroelectrics is widely unknown. The paper is devoted to the well-defined preparation of nanoscaled ferroelectrics and to investigations into the influence of size and microstructure effects on their nonlinear properties. Different metal/ferroelectric/metal-(MFM) and metal/ferroelectric/semiconductor-(MFS) heterostructures were prepared. The ferroelectric materials used are PZT and bismuth titanate. The nonlinear dielectric properties where analyzed by inspecting the amplitude-frequency-characteristics of a nonlinear series resonance circuit, which contained the heterostructures as nonlinear capacitance.