AMORPHIZATION AND CRYSTALLINE REGROWTH OF GDBA2CU3O7 THIN-FILMS BY ION-IMPLANTATION AND RTA

Thin films (about 300 nm) of GdBa2Cu3O7 (GBCO), sputtered onto MgO sub strates, have been implanted with Ne-20(+) ions, to doses of 5 x 10(14 ) ions cm(-2) (200 keV) and 3 x 10(14) ions cm(-2) (150 keV). Either i mplant causes amorphization above a damage threshold, the former exten ding throughout the film thickness, while the latter leaves some cryst alline material near to the substrate interface. Rapid thermal anneali ng (20 s, in oxygen, at a temperature around 840 degrees C), induces r ecrystallization, which can lead to a recovery of the superconducting phase. By patterning the film with arrays of dots, it is possible to r etain columnar crystalline seeds (masked from the amorphizing radiatio n by the dots) surrounded by an amorphous field. Subsequent annealing will induce solid-solution grain growth, leading to arrays of c-axis-o riented crystals with centres in defined positions. The ultimate aim i s to extend this seeded crystal growth to cover the entire film area. While TEM is the preferred method for following the grain growth, a te chnique of differentially etching amorphous, micro-polycrystalline and polycrystalline material has been devised to speed up characterizatio n. Results are presented from T-c, XRD, optical microscopy, and TEM in vestigations.