Fabrication and barrier diagnostics of superconductive tunnel junctions on Nb-Sn and V-Si

The procedures found to lead to good tunnel junctions on the Al5 superconductor Nb-Sn are described. The use of an acetic acid atmosphere and/or oxidized Si layer barriers is shown to be particularly effective. The role of excess Sn in good oxide barrier formatiom on bare Nb-Sn is discussed. These results are related to earlier work using oxidized Si barriers on V
3
Si.