Publication Type:Journal Article
Source:Journal of Applied Physics, Volume 98, Number 12 (2005)
Keywords:Capacitance, Electric currents, electric potential, Electric space charge, electrodes, ferroelectricity, Pb (Zr, Polarization, Richardson's constant, Schottky contacts, Semiconductor materials, Space-charge density, Surface properties, thin films, Ti) O <sub>3</sub> thin films
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 acceptorlike level. The model is applied on a set of metal- Pb (Zr,Ti) O3 -metal samples with different ZrTi ratios, deposited by different methods, and having different thicknesses, electrode materials, and electrode areas. Values around 1018 cm-3 were estimated for the hole concentration from capacitance-voltage measurements. The space-charge density near the electrode, estimated from current-voltage measurements, is in the 1020 - 1021 cm-3 range. The total thickness of the interface layer ranges from 3 to 35 nm, depending on the ZrTi ratio, on the shape of the hysteresis loop, and on the electrode material. The simulated I-V characteristics is fitted to the experimental one using the potential barrier and Richardson's constant as parameters. The potential barrier is determined to be in the 1.09-1.37 eV range and Richardson's constant is 520 A cm-2 K-2. © 2005 American Institute of Physics.
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