We present intrinsic tunneling spectroscopy measurements on small Bi2Sr2CaCu2O8+x mesas. The tunnel conductance curves show both sharp peaks at the superconducting gap voltage and broad humps representing the c-axis pseudogap. The superconducting gap vanishes at Tc, while the pseudogap exists both above and below Tc. Our observation implies that the superconducting and pseudogaps represent different coexisting phenomena.

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Using advanced sample engineering we performed simultaneous measurements of interlayer tunneling characteristics and in situ monitoring of temperature in Bi(2)Sr(2)CaCu(2)O(8 + delta) (Bi-2212) mesas. Together with a systematic study of size dependence of interlayer tunneling, this allowed unambiguous discrimination between artifacts of self-heating and gaps in the electronic spectra of Bi-2212. Such a confident spectroscopic information, which is not affected by self-heating or surface deterioration, was obtained for the first time for a high-T(c) superconductor. We also derived general expressions and formulated main principles of self-heating valid for a large variety of materials.