Site-Selective Enhancement of Superconducting Nanowire Single-Photon Detectors via Local Helium Ion Irradiation

Abstract

Achieving homogeneous performance metrics between nominally identical pixels is challenging for the operation of arrays of superconducting nanowire single-photon detectors (SNSPDs). Here, we utilize local helium ion irradiation to post-process and tune single-photon detection efficiency, switching current, and critical temperature of individual devices on the same chip. For 12nm thick highly absorptive SNSPDs, which are barely single-photon sensitive prior to irradiation, we observe an increase of the system detection efficiency from $<0.05\%$ to $(55.3\pm 1.1)\%$ following irradiation. Moreover, the internal detection efficiency saturates at a temperature of 4.5 K after irradiation with $1800\mathrm{ions}{\mathrm{nm}}^{-2}$. For irradiated 10 nm thick detectors we observe a doubling of the switching current (to $20\mu \mathrm{A}$) compared to 8 nm SNSPDs of similar detection efficiency, increasing the amplitude of detection voltage pulses. Investigations of the scaling of superconducting thin film properties with irradiation up to a fluence of $2600\mathrm{ions}{\mathrm{nm}}^{-2}$ revealed an increase of sheet resistance and a decrease of critical temperature towards high fluences. A physical model accounting for defect generation and sputtering during helium ion irradiation is presented and shows good qualitative agreement with experiments.

12 pages, 11 Figures

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Cited by in corpus (4)

• Sputtered NbN Films for Ultrahigh Performance Superconducting Nanowire Single-Photon Detectors
• Current-Crowding-Free Superconducting Nanowire Single-Photon Detectors
• Impact of helium ion irradiation on the thermal properties of superconducting nanowire single-photon detectors
• Origin of performance enhancement of superconducting nanowire single-photon detectors by He-ion irradiation