Local anodic oxidation of superconducting NbN thin films by an atomic forcemicroscope

Abstract

A local anodic oxidation technique has been applied to create oxidized nanowires onsuperconducting NbN thin films using an atomic force microscope (AFM) with aconductive probe. The AFM surface topography shows that both the width and height ofthe oxidized nanowires increase with increasing applied probe voltage under a certainrelative humidity and a probe scan rate. The resistances of the NbN microbridges with andwithout an oxidized nanowire crossing were measured, and the results indicate thatthe oxidized nanowires with height of more than 8 nm are fully oxidized. TheR–T andI–V characteristics of the NbN microbridges with the oxide wire of less than 8 nm were alsoobtained and analyzed. Methods for fabricating devices such as superconducting singlephoton detectors and superconducting hot electron bolometer mixers using this technologyare discussed.