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Study on the internal field and conduction mechanism of atomic layer deposited ferroelectric Hf0.5Zr0.5O2 thin films.
- Source :
- Journal of Materials Chemistry C; 6/28/2015, Vol. 3 Issue 24, p6291-6300, 10p
- Publication Year :
- 2015
-
Abstract
- The internal field (E<subscript>int</subscript>) in ferroelectric films is an important factor which can affect the reliability of practical devices utilizing two memory states which results from the remanent polarizations of ferroelectric films. In the current work, the E<subscript>int</subscript> in TiN/Hf<subscript>0.5</subscript>Zr<subscript>0.5</subscript>O<subscript>2</subscript>/TiN capacitors was controlled by changing the annealing atmosphere (N<subscript>2</subscript>, O<subscript>2</subscript>, and forming gas). The magnitude of negative E<subscript>int</subscript> in O<subscript>2</subscript>-annealed samples was the largest, whereas that in the forming gas-annealed sample was the smallest. The magnitude of E<subscript>int</subscript> can be understood based on the asymmetric distribution of oxygen vacancies near top and bottom TiN electrodes. Despite the large magnitude of E<subscript>int</subscript>, the two remanent polarizations can be reliably retained due to the large coercive electric field of Hf<subscript>0.5</subscript>Zr<subscript>0.5</subscript>O<subscript>2</subscript> films, and this is expected to be beneficial for application in semiconductor memory devices. During the repetitive electric field cycling for the wake-up process, the change in E<subscript>int</subscript> in O<subscript>2</subscript>- and forming gas-annealed samples showed the opposite tendency: the magnitude of E<subscript>int</subscript> in the O<subscript>2</subscript>-annealed Hf<subscript>0.5</subscript>Zr<subscript>0.5</subscript>O<subscript>2</subscript> film decreased, whereas that in the forming gas-annealed film increased. This difference is believed to be due to the redistribution of oxygen vacancies with electric field high enough for the migration of oxygen vacancies. The conduction mechanism of electrons through Hf<subscript>0.5</subscript>Zr<subscript>0.5</subscript>O<subscript>2</subscript> films was also examined, and the results fitted best with the Poole–Frenkel emission model with the shallow traps for all the samples with a reasonable optical dielectric constant value for Hf<subscript>0.5</subscript>Zr<subscript>0.5</subscript>O<subscript>2</subscript>. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 20507526
- Volume :
- 3
- Issue :
- 24
- Database :
- Complementary Index
- Journal :
- Journal of Materials Chemistry C
- Publication Type :
- Academic Journal
- Accession number :
- 103192590
- Full Text :
- https://doi.org/10.1039/c5tc01074h