2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/167491We perform a detailed study of temperature, bias and doping dependance of interlayer transport in the layered high temperature superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$. We observe that the shape of interlayer characteristics in underdoped crystals exhibit a remarkable crossover at the superconducting transition temperature: from thermal activation-type at $T>T_c$, to almost $T-$independent quantum tunneling-type, at $T<T_c$. Our data indicates that the interlayer transport mechanism may change with doping: from the conventional single quasiparticle tunneling in overdoped, to a progressively increasing Cooper pair contribution in underdoped crystals.10 pages, 10 figuresSuperconductivitytext