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Dielectric relaxation of high-k oxides

Chun Zhao1, Ce Zhou Zhao12*, Matthew Werner34, Steve Taylor1 and Paul Chalker3

Author Affiliations

1 Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool L69 3GJ, UK

2 Department of Electrical and Electronic Engineering, Xi’an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China

3 Department of Engineering, Materials Science and Engineering, University of Liverpool, Liverpool L69 3GH, UK

4 Nanoco Technologies Ltd, Manchester M13 9NT, UK

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Nanoscale Research Letters 2013, 8:456  doi:10.1186/1556-276X-8-456

Published: 1 November 2013

Abstract

Frequency dispersion of high-k dielectrics was observed and classified into two parts: extrinsic cause and intrinsic cause. Frequency dependence of dielectric constant (dielectric relaxation), that is the intrinsic frequency dispersion, could not be characterized before considering the effects of extrinsic frequency dispersion. Several mathematical models were discussed to describe the dielectric relaxation of high-k dielectrics. For the physical mechanism, dielectric relaxation was found to be related to the degree of polarization, which depended on the structure of the high-k material. It was attributed to the enhancement of the correlations among polar nanodomain. The effect of grain size for the high-k materials' structure mainly originated from higher surface stress in smaller grain due to its higher concentration of grain boundary.

Keywords:
Frequency dispersion; High-k; Grain size; Dielectric relaxation