Growth evolution of Bi2Sr2CaCu2O8+δ thin films deposited by infrared (1064nm) pulsed laser deposition

Post Deposition Heat Treatment Effects on Ceramic Superconducting Films Produced by Infrared Nd:YAG Pulsed Laser Deposition

“…The rapidly quenched films is thinner compared to partial melted films with an average thickness of about 2 µm. Both films show small amount of spheroidal particulates after heat treatment [10]. XRD measurements on the partial melted and rapidly quenched Bi-2212 films is shown in figure 2.…”

“…It has been observed that IR PLD Bi-2212 films require partial melting and annealing to allow uniform diffusion and migration of Bi-2212 materials on MgO substrate forming smoother film [10]. This attributed to the micron-size spheroidal grains trasferred on the substrate by the IR laser during deposition [10]. Hence, heat treatment is required to facilitate growth, flatten and densify the material producing much thinner films.…”

“…This is a common feature of Y-123 films especially when solid state sintered targets are used as the material source for the deposition [15,21]. While the heat treatment helps in densifying the grains, it also aids in coalescence of grains and forming an alignment of the material relative to the substrate orientation [10]. The appearance of rectangular grains could be a result of incongruent melting of Y-123 at rapid thermal heating at 1000 • C and the thickness of the films.…”

“…We are also unable to see micro-cracks initially observed in the as-deposited films. This is due to annealing that result to removal of pores and enlargement of grains [9,10]. The growth of a-axis grains also contribute to dispersion of micro-cracks [15].…”

“…This process is either performed in-situ or ex-situ and part of the post heat treatment [4,18]. These results implies that post heat treatment is necessary to homogenize the composition of the film and improve the critical temperarure T c [1,4,19] only about 58 K and for Bi-22Y2, the highest T c is 90.5 K at 25% Y concentration [9,10]. Y substituted Bi-2212 films grown by IR PLD show drop in magnetoresistance and improved critical current density J c [3].…”