Sputtering of YBa2Cu3O7−δ/NdAlO3/YBa2Cu3O7−δ trilayers

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Abstract
Epitaxial YBa2Cu3O7−δ/NdAlO3/YBa2Cu3O7−δ‐trilayers were grown by sputtering from stoichiometric targets. The YBa2Cu3O7−δ (YBCO) films were deposited by dc‐magnetron sputtering. For the NdAlO3 films, rf‐magnetron sputtering was used. The individual YBCO films revealed critical‐current densities up to 3×106 A/cm2 at 77 K. The bilayer and trilayer structures were characterized by x‐ray diffraction, Rutherford backscattering spectroscopy, and transmission electron microscopy (TEM). The channel yield χmin of the YBCO film on top was 15% for an in situ deposited trilayer. The epitaxial growth of the subsequent layers was proved by cross‐sectional TEM. Although the NdAlO3 layer contained misoriented grains, the top YBCO layer grows in single orientation over these areas. Preliminary electrical measurements show that NdAlO3 is a useful insulating dielectric for microelectronic applications.