PATTERNING OF THIN-FILM HIGH-T-c CIRCUITS BY THE LASER-WRITING METHOD

We report our studies on a laser-based two-dimensional patterning technique, which implements a focused beam from a cw Ar-ion laser to locally heat-up an epitaxial Y-Ba-Cu-O film in a controlled (oxygen-rich or oxygen-poor) atmosphere. Our results show that the laser-writing method enables a reproducible fabrication in the same film, oxygen depleted (semiconducting) regions next to enriched ones (superconducting), in a manner similar to n- and p-type diffusion regions in semiconductors. A number of test structures, laser written in initially oxygen-rich or oxygen poor films deposited on MgO, SrTiO3, and LaAlO3 single crystals, have been measured. The best, very homogeneous superconducting (oxygen-rich) circuits were patterned in oxygen-depleted YBCO deposited on the LaAlO3 substrates. The structures exhibited 0.5-K-wide superconducting transition, T-c0 = 89.5 K, and Je above 10(5) A/cm(2) Our oxygen-poor (semiconducting) lines, laser written in superconducting YBCO, were characterized by a thermally activated transport and were insulating at low temperatures.