Experimental studies to enlarge kinetic inductance of NbN thin films using the effects of quality and thickness of the film are made by measuring Fiske current steps in the current-voltage (I-V) characteristics of NbN/Pb-In Josephson junctions. Experiments demonstrate that the specific kinetic inductance LK can be enlarged over a wide range by changing stoichiometry of the film, as well as by making the film thickness thin, and that this enlargement becomes larger by both effects when the film thickness is in an ultra thin regime. This inductance is shown to be well fitted to LK=µ0λ2/d, where µ_0 isthevacuumpermeability, d isthethickness, and λ isthemagneticpenetrationdepthinthedirtylimit. Inthepresentexperimentweattainedtheinductanceashighas L_K=130 pHbythecombinedeffectsofimpurityandthicknessforafilmwith d=30 nm.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)