Titanium nitride (TiN) and superconducting YBa 2 Cu 3 O 7 (YBCO) thin films have been deposited sequentially on SrTiO 3 (STO)(100) substrates by in situ pulsed laser ablation. The TiN films were originally intended to serve as the lower contact electrode of the c-axis YBCO thin films. It was found that, although high-quality YBCO films could be obtained with the YBCO/TiN/STO(100) bilayer structure, the TiN(100) layer was oxidized which changed the structure into YBCO/TiO 2 /STO(100) during YBCO

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... deposition. Comparative studies of depositing YBCO films directly onto a dc-sputtered TiO 2 /STO(100) template conventionally used in the selective epitaxial growth (SEG) process have, however, resulted in formation of a nonsuperconducting YBCO top layer. The characteristics of the resultant TiO 2 layers obtained using various processes were analyzed to delineate the apparent discrepancies.