Evaluation of AlOx barrier thickness in Nb Josephson junctions using anodization profiles

Using anodization profiles, we have analyzed the thin AlOxAl tunneling barrier in a Nb/AlOxAl/Nb Josephson junction. We measured the voltage width at the AlOxAl barrier in the profiles and found that it is closely related to the AlOxAl 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.