High Temperature Superconducting nano-meanders made by ion irradiation

Low temperature Superconducting single photon detectors (SSPD) are suitable for quantum information and space communications applications. They show unrivaled performances from visible wavelength to 10μm that require complex cryogenics at 4K that limit applications. In this respect, high temperature superconductors (HTS) are attractive materials to design SSPDs operating at 40K.

We report the fabrication of YBa₂Cu₃O_7-x nano-meanders showing the highest aspect ratios ever reported so far (30nm thick, 100nm wide, 450μm long) by e-beam lithography and high-energy ion implantation [Amari et al. SUST (2018)]. DC measurements prove that superconducting properties in nanowires are preserved with respect to raw YBCO thin-film. We report large hysteretic IV curves in our nanowires, which is a key requirement for hot-spot creation in SSPD. The inductive part of the nanowires plays an important role in the dynamics of the detector. We study the nanowire’s inductance using a resonant method over a wide range of temperature up to T_C. The London penetration depth around 190nm extracted from the microwave measurement confirms that superconducting properties are conserved. Our ion irradiation technique paves the way for a suitable nanofabrication process of robust SSPDs made of HTS materials.