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Phonon modes, dielectric constants, and exciton mass parameters in ternary MgxZn1−xO

Published online by Cambridge University Press:  01 February 2011

Carsten Bundesmann ,
Michael Lorenz ,
Marius Grundmann  and
Mathias Schubert
Carsten Bundesmann
Affiliation:
[email protected], Universitaet Leipzig, Institut fuer Experimentelle Physik II, Linnéstr. 5, Leipzig, -, 04103, Germany
Michael Lorenz
Affiliation:
[email protected], Universität Leipzig, Institut für Experimentelle Physik II, Leipzig, N/A, 04103, Germany
Marius Grundmann
Affiliation:
[email protected], Universität Leipzig, Institut für Experimentelle Physik II, Leipzig, N/A, 04103, Germany
Mathias Schubert
Affiliation:
[email protected], University Nebraska-Lincoln, Department of Electrical Engineering, and Center for Materials Research and Analysis, Lincoln, Nebraska, 68588-0511, United States
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Abstract

The long-wavelength optical phonons and dielectric constants of PLD-grown MgxZn1−xO films are studied by combination of infrared spectroscopic ellipsometry and Raman scattering spectroscopy. The ternary alloy MgxZn1−xO exhibits a phase transition with change of coordination number from four-fold coordinated, hexagonal wurtzite structure (ZnO) to six-fold coordinated, cubic rocksalt structure (MgO). It is found that both phonon mode frequencies and dielectric constants change abruptly upon phase transition, which is assigned to the change of coordination number. The change of dielectric constants can be related to the change of electronic properties, for instance, the exciton binding energy. In a simple approach, the exciton binding energy depends on the reduced exciton mass and the static dielectric constant. By comparison with experimental values of the exciton binding energies it is found that the reduced exciton mass must increase by a factor of about two upon face transition from wurtzite to rocksalt structure.

Keywords

infrared (IR) spectroscopyoxidealloy
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 928: Symposium GG – Current and Future Trends of Functional Oxide Films , 2006 , 0928-GG05-03
Copyright
Copyright © Materials Research Society 2006

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References

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