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Investigation of contact phenomena in ferroelectric capasitor nanostructures Ir/PZT/Pt

DOI 10.18127/j22250999-201804-05


A.N. Antonovich ‒ Post-Graduate Student, MIREA ‒ Russian Technological University (Moscow)
A.A. Petrushin ‒ -Graduate Student, MIREA ‒ Russian Technological University (Moscow)
Е-mail: babaganusshh@gmail
Yu.V. Podgorny ‒ Ph.D. (Eng.), Leading Research Scientist, MIREA ‒ Russian Technological University (Moscow)

Ferroelectric films and capacitors based on them are the main elements of the non-volatile memory FeRAM. Electrodes (electrode materials) have a significant impact on the characteristics of FeRAM elements, including leakage currents. The investigation of charge transport mechanisms allows us to obtain new knowledge about the nature of the metal/ferroelectric interface and the physical phe-nomena that occur in the bulk of the film. This is necessary to understand the problems of FeRAM reliability, such as fatigue, imprint, polarization relaxation, resistance degradation and breakdown. Ferroelectric capacitor Ir-PZT-Pt were used as the object of study. The investigation of the steady state current was carried out by the static voltage-step method using a picoammeter with an integrated constant voltage source Hewlett Packard 4140B. The identified transport mechanisms (Schottky emission, ohmic current) do not allow a full description of the leakage current in the Ir-PZT-Pt structure in a wide range of applied voltages. In the field of strong fields, the functioning of traditional conduction mechanisms space charge limited current, the emission of Poole-Fraenkel and hopping conduction are not confirmed. These mechanisms are associated with the presence of a large number of traps in the band gap of the volume of a ferroelectric, which, apparently, are practically absent in our structures. Analysis of the current-voltage characteristics of the thin-film Ir-PZT-Pt capacitors (their asymmetry) indicates a significant influence on the dependence of the leakage current on the voltage of the electrode-ferroelectric interface. For the first time, the use of the induced current method for studying MSM structures made it possible to reliably determine the presence and thickness of depleted region near the interface layers in the Ir-PZT-Pt structure.

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