Preparation of Thin Films by a Bipolar Pulsed-DC Magnetron Sputtering System Using Ca₃Co₄O₉ and CaMnO₃ Targets

Weerasak Somkhunthot, Nuwat Pimpabute, Tosawat Seetawan

Program of Physics and Science Center, Faculty of Science and Technology, Loei Rajabhat University, Loei, Thailand.
Thermoelectrics Research Center, Faculty of Science and Technology, Sakon Nakhon Rajabhat University, Sakon Nakhon, Thailand.

DOI: 10.4236/msa.2012.39094                

Abstract

The thin films were deposited on the glass substrates by an asymmetric bipolar pulsed-dc magnetron sputtering system using the Ca₃Co₄O₉ and CaMnO₃ Targets (n-type) targets of 60 mm diameter and 2.5 mm thickness. The targets were prepared from powder precursors, which obtained by a solid state reaction. Optical emissions from plasmas during sputter depositions of films were detected using a high resolution spectrometer. Thickness of thin film was estimated by Tolansky’s Fizeau fringe method and ellipsometic measurement. Crystal structures were studied from X-ray diffraction. The thermoelectric properties were assessed from Seebeck coefficient and electrical resistivity measurements at room temperature. The power factors were calculated. It was found that the optical emission spectrums showed that the Ca, Mn, Co and O atoms were sputtered from the targets onto glass substrates. As-deposited Ca-Co-O and Ca-Mn-O films thickness values were 0.435 ?m and 0.449 ?m, respectively. The X-ray diffraction patterns clearly showed amorphous nature of the as-deposited films. Determining thermoelectric properties of Ca-Co-O film gave Seebeck coefficient of 0.146 mV/K, electrical resistivity of 0.473Ω.cm, and power factor of 4.531 μW/m?K at room temperature. Ca-Mn-O film baring a high resistance was not the experimental determination of thermoelectric properties.

Keywords

Thermoelectric Thin Film; Ca₃Co₄O₉; CaMnO₃; Bipolar Pulsed-DC Magnetron Sputtering System

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	D. A. Glocker, S. I. Shah and W. D. Westwood, “Handbook of Thin Film Process Technology,” Institute of Physics Publication, Philadelphia, 1995.
[2]	J. Sellers, “Asymmetric Bipolar Pulsed DC: The Enabling Technology for Reactive PVD,” Surface and Coatings Technology, Vol. 98, No. 1-3, 1998, pp. 1245-1250.doi:10.1016/S0257-8972(97)00403-9
[3]	W. Somkhunthot, T. Burinprakhon, I. Thomas, V. Amorn- kitbamrung and T. Seetawan, “Bipolar Pulsed-DC Power Supply for Magnetron Sputtering and Thin Films Synthesis,” Elektrika: Journal of Electrical Engineering, Vol. 9, No. 2, 2007, pp. 20-26.
[4]	J. Curry, “NIST Atomic Spectra Database,” 2012.http://www.nist.gov/pml/data/asd.cfm
[5]	S. Tolansky, “An Introduction to Interferometry,” London: Kongmans, Green & Co. Ltd., London, 1955.
[6]	K. Jayachandran, “Electrical, Optical and Structural Studies in Bismuth, Antimony, Bismuth Oxide and Antimony Oxide Thin Films,” Ph.D. Thesis, Mahatma Gandhi University, Kerala, 1997.
[7]	B. V. Zeghbroeck, “Principles of Semiconductor Devices,” 2011. http://ecee.colorado.edu/~bart/book/
[8]	G. S. Nolas, J. Sharp and H. J. Goldsmid, “Thermoelectrics: Basic Principles and New Materials Developments,” Springer-Verlag, Berling, 2001.
[9]	L. J. van der Pauw, “A Method of Measuring the Resistivity and Hall Coefficient on Lamellae of Arbitrary Shape,” Philips Technical Review, Vol. 20, No. 8, 1958, pp. 220-224.
[10]	D. M. Rowe, “CRC Handbook of Thermoelectrics,” CRC Press, Boca Raton, 1995. doi:10.1201/9781420049718