Tunneling characteristics for Bi2212 intrinsic Josephson junctions with little influence of self-heating using short pulse technique on 60 ns time scale

A small mesa structure (10 μm × 10 μm, 15 nm thick) of intrinsic Josephson junctions in Bi₂Sr₂CaCu₂o_8+δ is employed to observe the tunneling characteristics and the superconducting gap magnitude by short pulse technique (short pulse interlayer tunneling spectroscopy). In the measurement on 60 ns time scale, the effect of self-heating is almost negligible in the sample, whose resistivity is as small as 10 Ωcm. In slightly overdoped region, the maximum Josephson current density increases from 0.85 to 2.1 kA/cm² with increasing doping level. The superconducting gap magnitude 2Δ decreases from 62 to 37 meV with increasing doping level. The value for 2Δ/k_BT_c decreases from 8.3 to 5.2 with increasing doping level. These values in slightly overdoped region are smaller than those in optimum and underdoped region.