Anisotropic thermoelectric properties in layered cobaltite A{sub x}CoO{sub 2} (A=Sr and Ca) thin films
- Advanced Technology Research Laboratories, Matsushita Electric Industrial Co., Ltd., 3-4 Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0237 (Japan)
We have fabricated epitaxial thin films of layered cobaltite A{sub x}CoO{sub 2} (A=Sr and Ca) on sapphire substrates by rf magnetron sputtering. The grown phase in the A{sub x}CoO{sub 2} films was found to be a monoclinic {beta}-phase of primitive layered cobaltites and the epitaxial orientation of the film could be controlled by the surface plane of the substrates. The resistivity parallel to the CoO{sub 2} layers {rho}{sub parallel} for the {beta}-Sr{sub x}CoO{sub 2} is as low as 2 m{omega} cm at room temperature and shows metallic behavior. The ratio of perpendicular resistivity {rho}{sub perpendicular} to {rho}{sub parallel} increases from 20 at room temperature to 90 at 3 K. More isotropic nature was observed in the Seebeck coefficient. Parallel Seebeck coefficients S{sub parallel} of A{sub x}CoO{sub 2} are approximately 60 {mu}V/K at room temperature and the perpendicular S{sub perpendicular} are about half of S{sub parallel}.
- OSTI ID:
- 20632699
- Journal Information:
- Applied Physics Letters, Vol. 85, Issue 5; Other Information: DOI: 10.1063/1.1776310; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANISOTROPY
CALCIUM COMPOUNDS
COBALT OXIDES
DEPOSITION
ELECTRIC CONDUCTIVITY
EPITAXY
MAGNETRONS
MONOCLINIC LATTICES
SAPPHIRE
SEEBECK EFFECT
SPUTTERING
STRONTIUM COMPOUNDS
SUBSTRATES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
THERMOELECTRIC PROPERTIES
THIN FILMS