CRYSTALLINITY DEPENDENCE OF MICROWAVE DIELECTRIC PROPERTIES IN (Ba,Sr)TiO3 THIN FILMS

• Published in: Japanese Journal of Applied Physics, Part 1 Part 1, 2003, Vol.42 (3), p.1315-1319
• Main Authors: Kim, T-G, Oh, J, Kim, Y, Moon, T, Hong, K S, Park, B
• Format: Article
• Language: English
• ISSN: 0021-4922
• DOI: 10.1143/jjap.42.1315

The dielectric properties of (Ba0.43Sr0.57)TiO3 (BST) thin films were investigated in the microwave-frequency range. The dielectric losses (tan d) and dielectric constants (e) were measured up to approximately 6 GHz using a circular-patch capacitor geometry. The deposition temperatures were varied from RT to 750 C to investigate the effects of crystallinity on the dielectric properties. As the film crystallinity was enhanced, the dielectric losses increased from 0.0024 plus/minus 0.0018 at RT to 0.0102 plus/minus 0.0017 at 750 C deposition. The dielectric constants varied from 10.29 plus/minus 0.02 to 243 plus/minus 1 in the same deposition-temperature range. Raman spectroscopy showed that the increase in dielectric losses of the BST thin films was correlated with the growth of microscopic polar regions induced by symmetry-breaking defects. Because the sizes of these regions are proportional to the dielectric constants of host lattices (crystallinity), dielectric losses increase with the deposition temperatures. 27 refs.