DEPOSITION AND TUNNELING PHENOMENA OF DC SPUTTERED BISRCACUO-BASED HETEROSTRUCTURES

We have produced Cu2O8+delta/Bi2Sr2YCu2O8+delta/Bi2Sr2CaCu2O8+delta he terostructures using a high pressure de sputtering technique. The film s have been deposited in situ at high oxygen pressure on (001) SrTiO3 substrates. X-ray diffraction and high resolution transmission electro n microscopy (HRTEM) showed highly c-axis oriented trilayers. TEM anal ysis showed sharp interlaces between the superconducting films and the barrier, without intermediate amorphous regions. The Bi2Sr2CaCu2O8+de lta layers had superconducting transition temperatures of 87 K, with D elta T-c less than or equal to 1 K, while the barrier layers showed a semiconductor-like behavior explained in terms of variable range hoppi ng process, At low temperatures the conductance versus voltage charact eristics exhibit peaks indicative of gap-like structures at about +/-3 0 mV, finite conductances at zero bias and flat backgrounds for energi es higher than 30 mV.