Characteristics of intrinsic tunnel junctions on Bi-2223 thin films

We have successfully fabricated a small-sized thin slack with a small numbe r of intrinsic junctions on (Bi,Pb)(2)Sr2Ca2CU3O10 + (x) thin films. Mesa s tructures with the junctions are fabricated on the surface of high-quality films prepared by rf-sputtering and subsequent heat treatment. I-V characte ristics along the c-axis for the thinnest stack show a B-branch structure w hich corresponds to six tunnel junction arrays and the edge structure which represents the superconductive gap. The estimated superconductive gap valu es strongly depend on the number of junctions in the fabricated stack. For the thin stacks with B-junctions, their gap values are about 65 mV at 4.2 K , which is two or three times as large as those previously reported for int rinsic junctions. (C) 1999 Elsevier Science Ltd. All rights reserved.