THERMOELECTRIC STUDY OF Y-BA-CU-O THIN-FILM ON MGO SUBSTRATE PREPARED BY RESISTIVE EVAPORATION

Thermoelectric measurements were carried out on Y-Ba-Cu-O thin film deposited on MgO substrate by resistive evaporation technique. A pulverized mixture of Y, BaF2 and Cu weighed in the atomic proportion was evaporated from resistively heated source onto a MgO substrate kept at 400-degrees-C using a simple vacuum system. The substrate temperature was then raised to 700-degrees-C for insitu heat treatment. Oxygen was injected through a nozzle placed close to subtrate surface, thus raising the pressure to about 7 Pa during the heat treatment, which lasted for about 15 minutes. The film was then gradually cooled down to room temperature and the pressure raised to atmospheric pressure. The films thus obtained were measured and the values of thermoelectric power measurements in the plane of the film were found to be close to the typical thermoelectric power values of crystalline Y-Ba-Cu-O superconductors. As expected, vanishing values of the thermoelectric power have been observed below 80 K. If the relation observed for sintered Y-Ba-Cu-O is applied for thin films, it suggests an extremely low oxygen deficiency.