Conductivity and tunneling in epitaxial Bi2Sr2Ca1-xYxCu2O8+delta thin films

We performed a study on the preparation conditions and transport properties of Bi2Sr2Ca1-xYxCu2O8+delta thin films, and carried out tunneling measurem ents in planar type junctions using a Bi2Sr2YCu2O8+delta (22Y2, for x = 1.0 0) layer for the insulation of two Bi2Sr2CaCu2O8+delta (2212, for x = 0.00) electrodes. The deposition of the films was carried out by a high oxygen p ressure de-sputtering technique. By increasing the yttrium content x the te mperature dependence of the electrical resistivity changes from a metallic to an insulating behavior. Our measurements show a decrease in the critical temperature T-c with increasing yttrium content. An energy gaplike structu re near 45 meV was observed in the planar-type junctions. The zero bias ano maly observed is interpreted in terms of the Anderson-Appelbaum model.