Effect of Electron Irradiation on the Performance of Superconducting Devices

Low-energy electron irradiation can significantly impact the performance of superconducting devices, including short-term rise in quasiparticle population as well as long-term changes to the surface electronic structure and morphology. Here, we explore the influence of low-energy electron beams on the performance of microfabricated superconducting Nb and Ta microwires in both in-situ and ex-situ conditions. The irradiation is implemented in a custom-made ultrahigh vacuum reaction system at electron energies ranging from 500eV to 20 keV. The substrate temperature during the irradiation can be varied from 350 to 7 K using a closed-cycle GM cryocooler. Variations in microwires' resistance and critical current are monitored in-situ using a high-speed oscilloscope and lock-in amplifiers. This is complemented by ex-situ characterization of microwires' superconducting parameters and atomic-scale surface morphology. The information on the behavior of the superconducting microwires as a function of electron energy, fluence, and irradiation temperature can provide valuable insights into the application of superconducting devices in environments with medium to high probability of electron radiation.