Laser patterning of YBa/sub 2/Cu/sub 3/O/sub x/ thin films protected by in-situ grown SrTiO/sub 3/ cap layer

We report our studies on laser processing techniques suitable for patterning of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) thin films, as well as YBCO/SrTiO/sub 3/ bilayers, consisting of in-situ grown YBCO films with 100-nm-thick single-crystalline SrTiO/sub 3/ cap layers. The patterning is achieved through both laser inhibition, in which an intense, focused laser beam locally melts YBCO transferring it into an insulating glass-like material, and laser writing, based on a laser-controlled diffusion of oxygen in or out of the YBCO film. We have found that oxygen easily migrates through the SrTiO/sub 3/ layer, allowing to reversibly convert the underlying YBCO film between the superconducting and semiconducting (virtually insulating at low temperatures) phases. Using laser inhibition and writing, we were able to form in a single YBCO/SrTiO/sub 3/ sample well-defined regions of various electrical properties, showing that laser processing can be successfully used in patterning and/or electrical trimming of multilayered YBCO circuits. Aging studies, performed on an almost 2-years-old laser-written YBCO film, showed a very good, both structural and electrical stability of our laser-processed structures.>