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Preliminary First Principles Study Of Hf and Zr Aluminates as Replacement High-k Dielectrics

Published online by Cambridge University Press:  21 March 2011

Michael Haverty
Affiliation:
Materials Science and Engineering, Stanford University, Stanford, CA 94305, U.S.A. Multiscale Simulation Laboratory, Stanford University, Stanford, CA 94305, U.S.A.
Atsushi Kawamoto
Affiliation:
Center For Integrated Systems, Stanford University, Stanford, CA 94305, U.S.A.
Gyuchang Jun
Affiliation:
Materials Science and Engineering, Stanford University, Stanford, CA 94305, U.S.A. Multiscale Simulation Laboratory, Stanford University, Stanford, CA 94305, U.S.A.
Kyeongjae Cho
Affiliation:
Multiscale Simulation Laboratory, Stanford University, Stanford, CA 94305, U.S.A.
Robert Dutton
Affiliation:
Center For Integrated Systems, Stanford University, Stanford, CA 94305, U.S.A.
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Abstract

Bulk Density Functional Theory calculations were performed on Hf and Zr substitutions for Al in κ-alumina. The lowest energy configuration found was an octahedrally coordinated Zr site. Zr dissolution was favorable with an enthalpy of -2eV/unit cell for forming Al1.875Zr0.125O3 from pure Zr and κ-alumina. Hf and Zr substitution for Al atoms introduced empty d-states below the conduction band edge reducing the Eg of pure κ-alumina (7.5eV) to 6.4-5.9eV. The edge of the valence band however remained fixed by the O p-state character. The substitution of Hf and Zr into the alumina structure may lead to a higher dielectric constant, but will also reduce Eg and result in a trade off in tunneling currents in devices.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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References

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