Barrier characteristic in Nb/Ni planar tunnel junctions

Fabrication of native Nb oxide barriers and their influence on the tunneling behavior of Nb/Ni planar junctions are investigated. Each junction film electrode was grown by magnetron sputtering technique and two methods were used to obtain the barrier. In the first method, a NbxOy oxide layer was formed at room conditions on top of Nb. In the second one, a saturated water vapor atmosphere is used to obtain the NbxOy layer. Samples prepared on these ways show different tunneling characteristics related with changes in the barrier. Characterization of the barrier was done by low-angle X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy.