Abstract:
It is shown that composite ion irradiation of a thin NbN film to a fluence of 8.5 $\cdot$ 10$^{16}$ cm$^{-2}$, smaller than the optimal one (10 $\cdot$ 10$^{16}$ cm$^{-2}$), can be used to create cryogenic integrated resistors if the values of the operating currents of the device are greater than all the characteristic transition currents for irradiated and stabilized by annealing films. At the same time, smaller resistance values per square are realized, which allows one to create smaller values of integrated resistance. It is demonstrated that annealing of the irradiated film at a temperature of 600$^\circ$C leads to a partial return of superconducting properties and is accompanied by the appearance of two superconducting transitions at critical current densities of 0.45 $\cdot$ 10$^6$ A/cm$^2$ and 1 $\cdot$ 10$^6$ A/cm$^2$, which must be taken into account when it is necessary to use stabilizing annealing at elevated temperature.
Keywords:NbN thin superconducting films, radiation methods for changing the atomic composition of thin-film superconductors, ion irradiation, cryogenic electronic devices.
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