Oxygen vacancy concentration as a function of cycling and polarization state in TiN/Hf0.5Zr0.5O2/TiN ferroelectric capacitors studied by x-ray photoemission electron microscopy

We have studied the field cycling behavior of microscopic TiN/Hf0.5Zr0.5O2/TiN ferroelectric capacitors using synchrotron-based soft x-ray photoemission electron microscopy. The oxygen vacancy ( V O) concentration near the top TiN/Hf0.5Zr0.5O2 interface is estimated from the reduction of Hf4+ to Hf3...

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Bibliographic Details
Published in:Applied physics letters 2022-05, Vol.120 (20)
Main Authors: Hamouda, Wassim, Mehmood, Furqan, Mikolajick, Thomas, Schroeder, Uwe, Mentes, Tevfik Onur, Locatelli, Andrea, Barrett, Nick
Format: Article
Language:English
Subjects:
Applied physics
Capacitors
Cycles
Electron microscopy
Ferroelectric materials
Ferroelectricity
Microscopy
Oxygen
Photoelectric emission
Polarization
Soft x rays
Synchrotrons
Vacancies
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Summary:We have studied the field cycling behavior of microscopic TiN/Hf0.5Zr0.5O2/TiN ferroelectric capacitors using synchrotron-based soft x-ray photoemission electron microscopy. The oxygen vacancy ( V O) concentration near the top TiN/Hf0.5Zr0.5O2 interface is estimated from the reduction of Hf4+ to Hf3+ as measured in the Hf 4f core level spectra. The V O concentration increases with field cycling and redistributes under the effect of the internal field due to the polarization. Upward pointing polarization slightly depletes the concentration near the top interface, whereas downward polarization causes V O drift toward the top interface. The V O redistribution after wake-up is consistent with shifts in the I–V switching peak. The Schottky barrier height for electrons decreases systematically with cycling in polarization states, reflecting the overall increase in V O.
ISSN:0003-6951
1077-3118
DOI:10.1063/5.0093125