  A modified model of metal-semiconductor contacts is applied to analyze the
capacitance-voltage and current-voltage characteristics of
metal-ferroelectric-metal structures. The ferroelectric polarization is
considered as a sheet of surface charge situated at a fixed distance from the
interface. The presumable high concentration of structural defects acting as
active electric traps is taken into account by introducing a deep acceptor-like
level. The model is applied on a set of metal-PZT--metal samples with different
Zr/Ti ratios, deposited by different methods, and having different thickness,
electrode materials, and electrode areas. The concentration of the free
carriers, the fixed charge density in the depletion region, the distance
between polarization charge and the physical interface, the potential barrier
were estimated.
