Influence of electron beam exposure dose on the properties of NbN superconducting nanowires

The controllable fabrication of superconducting nanowires is the key foundation for the high-performance applications such as single-photon detectors and quantum phase slip devices. Electron beam lithography, as a key technique for nanoscale patterning, may have a non-ignorable impact on the intrinsic physical properties of ultrathin superconducting films due to the interactions between the electron beam and the material. This study systematically examines how the electron beam exposure dose influences the superconducting properties and sheet resistance of NbN nanowires. The results show that, as the exposure dose increases, the normal-state sheet resistance of NbN nanowires significantly increases (with a maximum increase of 24%), acompanied by the reduce of activation energy of the phase slip. Meanwhile, although the superconducting critical temperature remains largely unchanged, the nanowires' ability to withstand magnetic fields at ultra-low temperatures diminishes with the increase of exposure dose. Analysis indicates that high-dose exposure introduces structural defects into the film, enhancing carrier scattering and thereby increasing electrical resistance. These findings not only define an optimal process window for fabricating high-performance superconducting nanowires but also highlight the potential of electron beam exposure as a localized method for tuning disorder in on-chip superconducting films, opening new possibilities for quantum device engineering.