Band-Pass Filters for 1.8 GHz Frequency Range Using Double-Sided YBCO/Au Films on CeO2-Buffered Sapphire
Microstrip band-pass filters for the frequency range of 1.8 GHz were manufactured using double-sided YBa2Cu3O7−δ (YBCO) films on CeO2-buffered 2-in. sapphire wafers. Their S-parameters were measured. To protect YBCO films against degradation in air, they were coated with gold. Microwave surface resistance Rs(T) was measured by the copper end-plate and microstrip resonator techniques. The Au coating was proven to suppress Q-factor of resonators and to drastically increase the insertion losses of filters. A significant peak of Rs(dAu) for 77 K at dAu ≈ 20 nm was experimentally observed. The peak is much higher and occurs at much lower dAu values than what is predicted by a simple electrodynamic calculation for the bilayer film. We suggest that this is due to a surface roughness, which was observed by atomic force microscopy. A dynamic proximity effect with an account of Andreev reflection may be also important to understand the obtained results.
Unable to display preview. Download preview PDF.
- 1.Z.-Y. Shen, High-Temperature Superconducting Microwave Circuits (Artech House, Boston, 1994).Google Scholar
- 2.J. Browne, Microwave & RF 32, 123 (1993).Google Scholar
- 3.N. Newman and W. G. Lyons, J. Supercond. 6, 119 (1993).Google Scholar
- 4.J.-S. Hong, M. J. Lancaster, R. B. Greed, D. Voyce, D. Jedamzik, J. A. Holland, H. J. Chaloupka, and J.-C. Mage, IEEE Trans. Appl. Supercond. 9, 3893 (1999).Google Scholar
- 5.M. Lorenz, H. Hochmuth, D. Natusch, H. Boerner, T. Thaerigen, D. D. Patrikarakos, J. Frey, K. Kreher, S. Senz, G. Kaestner, D. Hesse, M. Steins, and W. Schmitz, IEEE Trans. Appl. Supercond. 7, 1240 (1997).Google Scholar
- 6.A. G. Zaitsev, R. Schneider, J. Greek, G. Linker, F. Ratzel, and R. Smithey, Appl. Phys. Lett. 75, 4165 (1999).Google Scholar
- 7.I. B. Vendik, M. N. Gubina, A. N. Deleniv, and D. B. Kholodnyak, Zh. Tech. Fiz. 67, 83 (1997).Google Scholar
- 8.V. M. Pan, V. F. Tarasov, A. G. Popov, V. V. Vysotskii, M. Lorenz, A. N. Ivanyuta, and G. A. Melkov, Physica B 284-288, 915 (2000).Google Scholar
- 9.A. A. Abrikosov, Fundamentals of the Theory of Metals (Nauka, Moscow, 1987) (in Russian).Google Scholar
- 10.N. Terada, S. Kashivaya, H. Takashima, S. Ueno, M. Koyanagi, and H. Ihara, IEEE Trans. Appl. Supercond. 9, 1704 (1999).Google Scholar
- 11.A. F. Andreev, J. Exp. Theor. Phys. 46, 1823 (1964); 47 2222 (1964) (in Russian).Google Scholar
- 12.F. F. Mende and A. I. Spitsin, Surface Impedance of Superconductors (Naukova Dumka, Kiev, 1985) (in Russian).Google Scholar
- 13.A. G. Zaitsev, R. Woerdenweber, T. Koenigs, E. K. Hollmann, S. V. Rasumov, and O. G. Vendik, Physica C 264, 125 (1996).Google Scholar