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High quality Nb/Al-AlOx/Nb Josephson junctions have been fabricated by a novel process named the self-aligned contact process. After the definition of the junction area by a reactive ion etching (RIE) technique, the exposed Nb layer and the junction edge are anodized to protect against electrical shorts and an Al film is deposited as the etching stopper layer. After base electrode patterning by RIE, an insulation layer is deposited. The contact hole, with the diameter of the junction, for connecting a counter electrode and a wiring layer, can be made without registration because of the deposited Al film. The junctions fabricated by this process have exhibited excellent current-voltage characteristics (Vm =70 mV at the critical current density jJ =1.8 kA/cm2, Vm =11 mV at jJ =20 kA/cm2). [ABSTRACT FROM AUTHOR]

Reports on a study of microstructure of Nb/AlO[sub x]-Al/Nb Josephson junctions by cross-sectional transmission electron microscopy that yielded information regarding the junction barrier region. Formation of polycrystalline films with columnar structures by both thick Nb and Al; Current-voltage characteristics of the junctions.

Using anodization profiles, we have analyzed the thin AlOx-Al tunneling barrier in a Nb/AlOx-Al/Nb Josephson junction. We measured the voltage width at the AlOx-Al barrier in the profiles and found that it is closely related to the AlOx-Al thickness. We proposed a way to evaluate this thickness from the voltage width. The anodization profile is useful in diagnosing the 4.2 K critical current density of Josephson junctions even at room temperature. [ABSTRACT FROM AUTHOR]

Investigates the interfaces of niobium (Nb) Josephson junctions with an overlayer structure using cross-sectional transmission electron microscopy. Factors attributing the interface roughness between aluminum (Al) and Nb; Application of McMillan's proximity theory for Al/Nb interface analysis; Impact of thermal annealing on interface roughness.

Focuses on the transistor characteristics of a three-terminal structure on an insulating strontium titanium oxide substrate. Fabrication of a superconducting YBa[sub 2]Cu[sub 3]O[sub 7-x] emitter; Construction of the three-terminal structures on crystals; Formation of base leads by silver paste.

Examines the use of secondary ion mass spectrometry in observing niobium (Nb) Josephson junction structure changes. Significance of the absorbed water vapor layers in the junction structure; Comparison between the annealing changes of Nb base electrode and Nb counterelectrode; Effect of grain boundary diffusion on the interface.