We present measurements of the intrinsic quasi-particle conductivity along
the c-axis of 2212-BSCCO single-crystal mesa structures in the superconduct
ing and normal states. Direct measurement of the mesa temperature enables c
orrections to be made for self-heating and permits the acquisition of relia
ble I-V characteristics over a wide range of temperatures and voltages. Unl
ike a conventional superconductor, there is no evidence for any change in t
he quasiparticle conductivity at T-c, consistent with precursor pairing of
electrons in the normal state. At low temperatures the initial low-voltage
linear conductivity exhibits a T-2 dependence, approaching a limiting value
at zero temperature. (C) 2000 Elsevier Science B.V. All rights reserved.