Y-Ba-Cu Oxide Films Formed with Pulsed-Laser Induced Fragments

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Abstract
For the formation of Y-Ba-Cu oxide films by pulsed-laser sputtering, the dependence on laser energy density was first investigated over a wide range from 0.6 to 3 J/cm2 at 1.064 µm. Rutherford backscattering spectrometry proved that the composition of deposited films strongly depends on the energy density. Films formed at a narrow window of laser energy density from the sputtering threshold of 0.6 J/cm2 to 0.8 J/cm2 showed superconductivity with a T c onset at 81 K and zero resistance at 79 K in spite of an excess of Cu and Ba atoms after annealing in oxygen. The X-ray diffraction patterns showed that these films have highly preferred orientation of the c-axis, and scanning electron microscopy exhibited the texture of highly dense grains with large sizes of about 5 µm at the surface.