Enhanced Jc of MOD-YBCO Films by Modifying Surface States of CeO2 Buffer Layers on Sapphire Substrates

Simple and easy treatments for the CeO2 buffer layers on sapphire single crystal substrates were demonstrated to enhance the superconducting properties of the metalorganic YBa2Cu3O7-y films using (i) acid solution dipping, (ii) UV light irradiation, and (iii) thermal annealing. When the CeO2 buffer layers were exposed to UV light, water contact angles diminished drastically, however, an apparent effect on the superconducting properties was not observed. On the other hand after the thermal annealing at 750°C under the mixture of dry-air and N2 gas, superconducting current density of 1.4 MA/cm2 at 77.3K was achieved independent of treatment time.