Borkar, Hitesh and Barvat, Arun and Pal, Prabir and Shukla, A. K. and Pulikkotil, J. J. and Kumar, Ashok
(2016)
Polaron-electron assisted giant dielectric dispersion in SrZrO3 high-k dielectric.
Journal of Applied Physics, 119 (21).
ISSN 0021-8979
Abstract
The SrZrO3 is a well known high-k dielectric constant (similar to 22) and high optical bandgap (similar to 5.8 eV) material and one of the potential candidates for future generation nanoelectronic logic elements (8 nm node technology) beyond silicon. Its dielectric behavior is fairly robust and frequency independent till 470 K; however, it suffers a strong small-polaron based electronic phase transition (T-e) linking 650 to 750 K. The impedance spectroscopy measurements revealed the presence of conducting grains and grain boundaries at elevated temperature which provide energetic mobile charge carriers with activation energy in the range of 0.7 to 1.2 eV supporting the oxygen ions and proton conduction. X-ray photoemission spectroscopy measurements suggest the presence of weak non-stoichiometric O2- anions and hydroxyl species bound to different sites at the surface and bulk. These thermally activated charge carriers at elevated temperature significantly contribute to the polaronic based dielectric anomaly and conductivity. Our dielectric anomaly supports pseudo phase transition due to high degree of change in ZrO6 octahedral angle in the temperature range of 650-750 K, where electron density and phonon vibration affect the dielectric and conductivity properties. Published by AIP Publishing.
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