ELECTRIC-FIELD EFFECT ON THE ARTIFICIAL GRAIN-BOUNDARY OF BICRYSTAL YBA2CU3O7-DELTA FILMS

An ability of the artificial grain boundary of bicrystal YBa2Cu3O7-del ta thin films is demonstrated as the field effect channel of high T(c) field effect devices. The influence of field application on the chann el resistance is examined with a metal-insulator-semiconductor-type st ructure, in which a channel is arranged across the grain boundary. The field-induced change in the resistance of the grain boundary is enhan ced up to around 5% by lowering temperature below T(c) of adjoining YB a2Cu3O7-delta grains. The enhancement is explained not only by an incr ease in the dielectric constant of the gate insulator (SrTiO3) but als o by a reduction in the carrier density nearby the grain boundary. The latter is indeed a benefit to high T(c) field effect devices.