GROWTH-BEHAVIOR OF Y1BA2CU3O7-X SUPERCONDUCTING THIN-FILMS USING LASER-ABLATION TECHNIQUE

The growth behavior of Y1Ba2Cu3O7-x (YBCO) thin films on MgO substrate s synthesized by laser ablation deposition techniques has been investi gated. The effects of important parameters, i.e., substrate temperatur e, post annealing schemes, laser beam fluence and deposition chamber a tmosphere on the crystal structure, microstructure and superconductivi ty of the deposited films have been studied. Among those important dep ositing parameters, the plume to film interaction was observed to impo se the most prominent effect on the film characteristics. The films we re found to consist mainly of a noncrystalline phase whenever the subs trates were located either in the invisible or the supersonic zones of the plume. Only when the substrates are positioned in the reactive zo ne does the crystalline phase grow rapidly via a nucleation and growth mechanism. The (013) grains nucleate preferentially and are subsequen tly transformed into a (00m) orientation, possibly by diffusion. The n umber of (013) grains transformed increases with temperature used for step annealing and with time at that temperature.