The adverse effect of depositing RBa2Cu3O7-delta on nearly perfect latticematching substrates

Despite numerous attempts to optimize the deposition conditions, we have fo und that there is always a substantial resistive tail below the bulk T-c of EuBa2Cu3O7-delta and SmBa2Cu3O7-delta films deposited on nearly perfect la ttice matching SrTiO3 (STO) substrates. This is in contrast to the same fil ms deposited on YSZ, LaAlO3 (LAO) and NdGaO3 (NGO) substrates under similar conditions. The films on YSZ, LAO and NGO substrates have a sharp resistiv e transition without any tails, although the lattice match is poorer. We ha ve developed an interpretation of this adverse effect and a simple bi-layer process to get rid of the resistive tails.