EFFECTS OF 50 KEV H-2(-ION IMPLANTATION AND RAPID THERMAL ANNEALING ON THE MICROSTRUCTURE OF YBCO THIN-FILMS())

A YBCO film with thickness of about 200 nm was deposited on LaAlO3 [10 0] by direct current (d.c.) sputtering. The film, which was found to b e mainly c-axis orientated, was irradiated at room temperature with 50 keV H-2(+) ions to a dose of 1 x 10(16) cm(-2). This implantation des troyed the superconductivity and made the film textured, with the ''ep itaxial'' crystalline structure of the film being mainly maintained. T ransmission electron microscope studies show that there are a consider able number of amorphous islands, which are Y rich and Cu poor compare d with the 123 phase in the as-received YBCO film. These amorphous isl ands are found to be unstable under the irradiation, as after implanta tion some polycrystalline regions, rather than amorphous islands, can be seen by TEM. Rapid thermal annealing in flowing O-2 ambient can ind uce oxygen reordering and results in partial recovery of critical temp erature, T-c. After RTA, the polycrystalline regions have not changed.