Figure 1
Structure of an Al/AlOx/Al junction from scanning transmission electron microscopy (STEM) imaging and electron energy loss spectroscopy (EELS) analysis.
(a) A cross-sectional ADF STEM image showing different layers in a typical Al/AlOx/Al Josephson junction with AlOx formed by thermal oxidation directly on the bottom Al electrode. (b) A high resolution ADF STEM image of a junction area showing the tunnel barrier. Lattice fringes and atomic columns from crystalline Al region are visible. (c) Al-L23 EELS line-profile obtained across the tunnel junction, from top Al electrode, aluminium oxide tunnel barrier to bottom Al electrode. The inset shows the Al-L23 ELNES signal from the centre of the barrier after subtracting the contribution from the Al electrode.
