The effects of space charges on hysteresis loops and field distributions in ferroelectrics have been investigated numerically using the phenomenological Landau-Ginzburg-Devonshire theory. Cases with the ferroelectric fully and partially depleted have been considered. In general, increasing the number of charged impurities results in a lowering of the polarization and coercive field values.Squarer loops were observed in the partially depleted cases and a method was proposed to identify fully depleted samples experimentally from dielectric and polarization measurements alone. Unusual field distributions found for higher dopant concentrations have some interesting implications for leakage mechanisms and limit the range of validity of usual semiconductor equations for carrier transport. * Electronic address: pz212@cam.ac.uk † Also at Advanced Technology Team, Semiconductor R&D Center,

We have conducted a careful study of current-voltage (I-V ) characteristics in fully integrated commercial PbZr 0.4 Ti 0.6 O 3 thin film capacitors with Pt bottom and Ir/IrO 2 top electrodes. Highly reproducible steady state I-V were obtained at various temperatures over two decades in voltage from current-time data and analyzed in terms of several common transport models including space charge limited conduction, Schottky thermionic emission under full and partial depletion and Poole-Frenkel conduction, showing that the later is the most plausible leakage mechanism in these high quality films. In addition, ferroelectric hysteresis loops and capacitance-voltage data were obtained over a large range of temperatures and discussed in terms of a modified Landau-Ginzburg-Devonshire theory accounting for space charge effects. * Electronic address: pz212@cam.ac.uk † Also at Advanced Technology Team, Semiconductor R&D Center,

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Articles you may be interested inEnhancement of fatigue endurance in ferroelectric PZT ceramic by the addition of bismuth layered SBT Mechanical stress effects on Pb(Zr,Ti)O3 thin-film ferroelectric capacitors embedded in a standard complementary metal-oxide-semiconductor process Appl. Phys. Lett. Nature of nonlinear imprint in ferroelectric films and long-term prediction of polarization loss in ferroelectric memories J. Appl. Phys. 96, 6616 (2004); 10.1063/1.1805190 Downscaling of Pb(Zr,Ti)O 3 film thickness for low-voltage ferroelectric capacitors: Effect of charge relaxation at the interfaces

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