In situ controlled fabrication of stacks of high-T-c intrinsic Josephson junctions

Stacked series arrays of intrinsic Josephson (IJ) tunnel junctions have been fabricated on the surfaces of Bi2Sr2CaCu2O8+delta single crystals using photolithography and Ar-ion milling together with in situ monitoring of the resulting current-voltage (I-V) characteristics. The number of unit-cell-sized junctions in the stack (along the c-axis) may be varied from 1-5 to similar to 200 in a controlled way. The c-axis resistivity rho(c), estimated from the resistance of an individual tunnel junction is approximate to 30 Omega cm at 90 K. The temperature dependence rho(c)(T)proportional to exp(Lambda/T) with Lambda approximate to 43 meV, suggesting thermally activated hopping mechanism of transport in the c-axis direction. (C) 1997 American Institute of Physics.