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Abstract

After an ordinary mesa is fabricated on a piece of single crystal
Bi2Sr2CaCu2O8+delta, another ion milling concentrating on the center of
the mesa is carried out, resulting in a U-shaped structure with a very
thin stack of intrinsic Josephson junctions sitting at its bottom. By
using low energy in the milling and reducing the etching rates, we can
control the junction number precisely and even a single intrinsic
Josephson junction can be fabricated. The I-V characteristics for 4-,
3-, and 1-junction arrays are shown here to support the argument. In
the last case (a single junction), some typical structures are believed
to be attributable to the behavior of a
superconductor-insulator-superconductor (S-I-S) junction with an IcRn
product of 7.2 mV at 4.2 K, and a suppressed energy gap structure of
Delta = 12 meV. Various microwave-induced steps are observed in the
frequency range of 1-20 GHz. (C) 2004 Elsevier B.V. All rights reserved.