Optimization of electrical and
structural parameters of YBa2Cu3O7-x
thin-film electrodes of
bicrystal Josephson junctions with chemical and thermal treatments of
substrates
I. I. Gundareva 1,2, V. N. Gubankov 1,
Y. Divin 1,2
1Kotel’nikov
Institute of Radio Engineering and Electronics of Russian Academy of
Sciences
2Peter
Grünberg Institute, Forschungszentrum Jülich, Jülich, Germany
Received
March 20, 2013
Abstract. Effects of technological parameters on electrical and structural
properties of epitaxial YBa2Cu3O7-x thin films
have been studied. The YBa2Cu3O7-x thin films
were fabricated by dc sputtering and intended to be used as base electrodes of
Josephson junctions. The parameters of chemical and thermal treatments of
NdGaO3 substrates were found, which guarantee the high, up to 5⋅106À/ñm2 at the temperature of 78K, values of the critical current
densities for the c-axis YBa2Cu3O7-x
thin films with the widths of a few micrometers. In the case of the YBa2Cu3O7-x
films with tilted c-axes, the critical current density in the direction
of the tilt decreased with a decrease of the film width and in perpendicular
direction reached the values up 1.3⋅107À/ñì2. Voltage-current characteristics of the YBa2Cu3O7-x
films above the critical currents Ic were found to be good
described by an equation V = a(I - Iñ)b, where the b-indexes
were ranging from 2 to 3 depending on the c-axis tilt and the temperature
of substrate annealing in oxygen.
Keywords: high
temperature superconductivity, epitaxial thin films, Josephson junctions.