The role of nitrogen-related defects in high-k dielectric oxides: Density-functional studies

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© 2005 AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the authors and the American Institute of Physics. The following article appeared in Journal of Applied Physics, Volume 97, Issue 5 and may be found at http://scitation.aip.org/content/aip/journal/jap/97/5/10.1063/1.1854210.

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Journal Title

Journal ISSN

Volume Title

School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2005

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Mcode

Degree programme

Language

en

Pages

053704/1-13

Series

Journal of Applied Physics, Volume 97, Issue 5

Abstract

Using ab initio density-functional total energy and molecular-dynamics simulations, we study the effects of various forms of nitrogen postdeposition anneal(PDA) on the electric properties of hafnia in the context of its application as a gate dielectric in field-effect transistors. We consider the atomic structure and energetics of nitrogen-containing defects which can be formed during PDA in various N-based ambients: N2, N2+, N, NH3, NO, and N2O. We analyze the role of such defects in fixed charge accumulation, electron trapping, and in the growth of the interface SiO2 layer. We find that nitrogen anneal of the oxides leads to an effective immobilization of native defects such as oxygen vacancies and interstitial oxygen ions, which may inhibit the growth of a silica layer. However, nitrogen in any form is unlikely to significantly reduce the fixed charge in the dielectric.

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Keywords

high k, modelling, nitrogen, postdeposition anneal, hafnia, electric properties

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Citation

Gavartin, J. L. & Shluger, A. L. & Foster, Adam S. & Bersuker, G. I. 2005. The role of nitrogen-related defects in high-k dielectric oxides: Density-functional studies. Journal of Applied Physics. Volume 97, Issue 5. 053704/1-13. ISSN 0021-8979 (printed). DOI: 10.1063/1.1854210