Interlayer tunneling spectroscopy of mixed-phase BSCCO superconducting whiskers

In this work, we present a study on the interlayer tunneling spectroscopy of the mixed-phase BiSrCaCuO (BSCCO) superconducting whiskers. Cross-whisker junctions were prepared only by an annealing process without requiring a long lithography processes. The tunneling experiments were carried out on the cross-whisker junctions. A multiple superconducting energy gap in the cross-whisker junctions was observed, which is attributed to the presence of different doping levels of two Bi2Sr2CaCu2O8+δ phases (Bi-2212) rather than two different phases, Bi2Sr2CaCu2O8+δ and Bi2Sr2Ca2Cu3O8+δ (Bi-2212 and Bi-2223) in the BSCCO whiskers. The temperature dependence of the energy gaps were discussed in framework of the BCS temperature-dependence. On the other hand, the carrier concentration of the cross-whisker junction was changed by carrier injection process. Effects of the carrier injection on the critical current, Ic, and the interlayer tunneling spectroscopy (ITS) of intrinsic Josephson junctions (IJJ’s) were investigated in details.