Enhanced high temperature thermoelectric properties of Bi-doped c-axis oriented Ca3Co4O9 thin films by pulsed laser deposition.
Hng, H. H.
Yan, Q. Y.
Date of Issue2010
School of Materials Science and Engineering
Singapore Membrane Technology Centre
Ca3−xBixCo4O9 (x=0–0.4) thin films were deposited on single-crystal sapphire (0001) substrates by pulsed laser deposition. Structural characterizations indicated that these thin films exhibited perfect c-axis orientation and were well crystallized. Surface chemical states analysis confirmed Bi-substitution for Ca in the thin films with x<0.4. For the thin film with x=0.4, excessive Bi were found isolated within the film. Due to their perfect orientation, in-plane electrical properties of these thin films measured from 300 to 740 K were found to be comparable to those of the single crystals. Furthermore, Bi-substitution was noted for the reduced electrical resistivity and enhanced Seebeck coefficient. The above superior properties resulted in a high power factor of 0.81 mW m−1 K−2 at 740 K for thin film Ca2.7Bi0.3Co4O9, which was about 29% improvement as compared to that of pure Ca3Co4O9 thin film. The results suggested that Bi-doped Ca3Co4O9 thin films could be a promising candidate for thermoelectric applications at elevated temperatures.
DRNTU::Engineering::Materials::Microelectronics and semiconductor materials::Thin films
Journal of applied physics
© 2010 American Institute of Physics. This paper was published in Journal of Applied Physics and is made available as an electronic reprint (preprint) with permission of American Institute of Physics. The paper can be found at: [DOI: http://dx.doi.org/10.1063/1.3499324]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.