Bi2Sr2CaCu2O8+delta intrinsic Josephson junctions: Surface layer characterization and control

Intrinsic Josephson junctions on Bi2Sr2CaCu2O8+delta superconductors are fabricated using an in situ low-temperature cleavage technique, which allows for the fabrication of well-controlled surface CuO2 double layers of different doping levels. The low-voltage I-V characteristics and c-axis conductivity properties are discussed for both the surface junctions (D-I-D-' type) and inner junctions (D-I-D type) where D denotes a d-wave superconductor. Our results show that the experimental data can be satisfactorily described in terms of the theory taking account of the coherent process with a directional tunneling matrix element.