Patterning of thin-film high-T/sub c/ circuits by the laser-writing method

The authors report studies on a laser-based 2-D patterning technique that implements a focused beam from a continuous-wave (CW) Ar-ion laser to locally heat up an epitaxial Y-Ba-Cu-O film in a controlled (oxygen-rich or oxygen-poor) atmosphere. It is shown that the laser-writing method enables a reproducible fabrication in the same film of 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, SrTiO/sub 3/, and LaAlO/sub 3/ single crystals, have been measured. The best, very homogeneous superconducting (oxygen-rich) circuits were patterned in oxygen-depleted YBCO deposited in the LaAlO/sub 3/ substrates. The structures exhibited a 0.5-K-wide superconducting transition, T/sub c0/=89.5 K, and J/sub c/ above 10/sup 5/ A/cm/sup 2/.<>