Thermoelectric properties of epitaxial ScN films deposited by reactive magnetron sputtering onto MgO(001) substrates
Date of this Version
4-21-2013Citation
J. Appl. Phys. 113, 153704 (2013)
Abstract
Epitaxial ScN(001) thin films were grown on MgO(001) substrates by dc reactive magnetron sputtering. The deposition was performed in an Ar/N-2 atmosphere at 2 x 10(-3) Torr at a substrate temperature of 850 degrees C in a high vacuum chamber with a base pressure of 10(-8) Torr. In spite of oxygen contamination of 1.6 +/- 1 at. %, the electrical resistivity, electron mobility, and carrier concentration obtained from a typical film grown under these conditions by room temperature Hall measurements are 0.22 m Omega cm, 106 cm(2) V-1 s(-1), and 2.5 x 10(20) cm(-3), respectively. These films exhibit remarkable thermoelectric power factors of 3.3-3.5 x 10(-3) W/mK(2) in the temperature range of 600 K to 840 K. The cross-plane thermal conductivity is 8.3 W/mK at 800 K yielding an estimated ZT of 0.3. Theoretical modeling of the thermoelectric properties of ScN calculated using a mean-free-path of 23 nm at 300 K is in very good agreement with the experiment. These results also demonstrate that further optimization of the power factor of ScN is possible. First-principles density functional theory combined with the site occupancy disorder technique was used to investigate the effect of oxygen contamination on the electronic structure and thermoelectric properties of ScN. The computational results suggest that oxygen atoms in ScN mix uniformly on the N site forming a homogeneous solid solution alloy. Behaving as an n-type donor, oxygen causes a shift of the Fermi level in ScN into the conduction band without altering the band structure and the density of states. (C) 2013 AIP Publishing LLC [http://dx.doi.org/10.1063/1.4801886]
Discipline(s)
Nanoscience and Nanotechnology
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Copyright 2013 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in J. Appl. Phys. 113, 153704 (2013); and may be found at http://dx.doi.org/10.1063/1.4801886 . The following article has been submitted to/accepted by Journal of Applied Physics. After it is published, it will be found at. Copyright 2013, Polina V. Burmistrova, Jesse Maassen, Tela Favaloro, Bivas Saha, Shuaib Salamat et al. This article is distributed under a Creative Commons Attribution 3.0 Unported License.