Epitaxial deposition and properties of Bi2Sr2CaCu2O8+delta/Bi2Sr2YCu2O8+delta/Bi2Sr2CaCu2O8+delta trilayers

We have deposited Bi2Sr2CaCu2O8+delta/Bi2Sr2YCu2O8+delta/Bi2Sr2CaCu2O8+delta (2212/22Y2/2212) heterostructures by an in situ de sputtering technique at high oxygen pressures on (001) SrTiO3 substrates. The formation of highly c-axis oriented trilayers with sharp interfaces is demonstrated by x-ray diffraction and transmission electron microscope (TEM) analysis. Both the top and the bottom 2212 layers are superconducting below 87 K. Tunneling phenomena on junctions fabricated from these trilayers are observed. The conductance versus voltage curves at low temperatures exhibit a change of slope indicative of a gap structure at about 30 mV, a zero-bias peak, as well as linear background at high voltages. (C) 1996 American Institute of Physics.