We have produced Bi2Sr2CaCu2O8+delta/Bi2Sr2YCu2O8+delta/Bi2Sr2CaCu2O8+delta heterostructures using a high pressure de sputtering technique. The films have been deposited in situ at high oxygen pressure on (001) SrTiO3 substrates. X-ray diffraction and high resolution transmission electron microscopy (HRTEM) showed highly c-axis oriented trilayers. TEM analysis showed sharp interlaces between the superconducting films and the barrier, without intermediate amorphous regions. The Bi2Sr2CaCu2O8+delta layers had superconducting transition temperatures of 87 K, with Delta T-c less than or equal to 1 K, while the barrier layers showed a semiconductor-like behavior explained in terms of variable range hopping process, At low temperatures the conductance versus voltage characteristics exhibit peaks indicative of gap-like structures at about +/-30 mV, finite conductances at zero bias and flat backgrounds for energies higher than 30 mV.

We have produced Bi2Sr2CaCu2O8+delta/Bi2Sr2YCu2O8+delta/Bi2Sr2CaCu2O8+delta heterostructures using a high pressure de sputtering technique. The films have been deposited in situ at high oxygen pressure on (001) SrTiO3 substrates. X-ray diffraction and high resolution transmission electron microscopy (HRTEM) showed highly c-axis oriented trilayers. TEM analysis showed sharp interlaces between the superconducting films and the barrier, without intermediate amorphous regions. The Bi2Sr2CaCu2O8+delta layers had superconducting transition temperatures of 87 K, with Delta T-c less than or equal to 1 K, while the barrier layers showed a semiconductor-like behavior explained in terms of variable range hopping process, At low temperatures the conductance versus voltage characteristics exhibit peaks indicative of gap-like structures at about +/-30 mV, finite conductances at zero bias and flat backgrounds for energies higher than 30 mV.