NbN/Nb Josephson Junction with a Plasma Oxidized Barrier

Abstract
Oxide growth on a niobium nitride film formed by rf plasma oxidation was studied using NbN/Nb-oxide/Nb tunnel junctions. A model of the oxide growth on niobium nitride is discussed to compare the oxidation on a film with a pre-oxidized layer formed by thermal oxidation and a film without the pre-oxidized layer. Using a thermally pre-oxidized layer, a junction with high critical current density can form with good controllability.