RAMAN-SPECTROSCOPIC STUDY OF NB ALOX-AL/NB JOSEPHSON-JUNCTIONS/

We have studied the AlOx barrier composition of niobium (Nb) Josephson junctions with a Nb/AlOx-Al/Nb structure using Raman spectroscopy at 10 K. We have observed both Al-O and Al-OH modes of an AlOx barrier wi th a few nm thickness in the Raman spectra through Nh counter electrod e. For a structure annealed at 300 degrees C, the Al-O mode intensity increases and the Al-OH mode intensity decreases. This contributes to a change in the critical current of the junction after annealing.