Conception of a passive dead layer at the metal-ferroelectric interface plays an important role in electrical properties characterization of metal-ferroelectric-metal structures. It is commonly supposed that the dead layer is a reason for properties degradation with the ferroelectric film thickness decrease, including decreasing polarization, hysteresis slope, dielectric permittivity, etc. We perform dead layer analysis at the PZT-Pt interface for the films with different internal structure. The dead layer thickness δ was calculated from the hysteresis tips obtained at different voltages to exclude leakage influence. For comparison, the dead layer thickness was estimated from the dielectric permittivity-thickness dependencies and from hysteresis slope technique proposed by A.Tagantsev [1]. Capacitance and hysteresis tips techniques give a good correlation for dense polycrystalline films: δ ~ 2.5 Å. For porous PZT films, the dead layer thickness demonstrate higher values: δ = 12 Å for capacitance measurements, and δ = 5.8 Å for hysteresis measurements. The reason is higher leakage currents in porous PZT films causing shunting of dead layer capacitance. Tagantsev’s technique gives twice-triple lower δ values, which does not correlate with low-field dielectric permittivity measurements.
[1] A. K. Tagantsev, M. Landivar, E. Colla, and N. Setter, J. Appl. Phys. 78, 2623 (1995).