High Tc superconducting Y‐Ba‐Cu‐O oxide films by sputtering and molecular beam epitaxy: Morphology, structural characterization and superconducting properties

We have studied the morphology, structure and superconducting properties high Tc oxide films, mostly in the Y‐Ba‐Cu‐O sytem, prepared by various sputtering techniques (diode and magnetron sputtering) and molecular beam epitaxy (MBE). In the as‐deposited condition the chemical homogeneity both across the film and through the thickness is excellent as measured by Rutherford backscattering spectrometry (RBS). Post oxygen annealing at temperature above 800°C yields the orthorhombic superconducting phase as revealed by the x‐ray diffraction. High‐quality epitaxially grown Y1Ba2Cu3O7−x films deposited on single‐crystal SrTiO3 substrates with various orientations were obtained with a narrow rocking curve (<0.3°) in the direction perpendicularly to the film plane. Also, for the first time we observed the electron channeling in this class of materials. Sharp superconducting resistive transitions with Tc(R=0) above 89K and critical current density at 77K have been reproducibly achieved.