Presentation Information
[EDP1-08]Photoresponse of superconducting nanostrips based on NdFeAs(O,H)
*Atsuro Yoshikawa1, Daichi Aoki1, Shunya Tomioka1, Ibuki Washitani1, Takafumi Hatano1, Hiroki Kutsuma2, Taro Yamashita2, Hiroshi Ikuta1 (1. Nagoya Univ. (Japan), 2. Tohoku Univ. (Japan))
Keywords:
iron-based superconductor,photon detector,nanofabrication
Superconducting single photon detectors (SSPDs) are essential for various quantum technologies because they outperform semiconductor-based ones. To achieve high performance, nanostrips with a line width of about 100 nm are typically used for SSPDs. However, such nanofabrication is technically challenging, and most SSPDs are based on superconductors that have a low critical temperature (Tc) and can operate only at 4 K or lower. To increase the operating temperature, we have been investigating the potential of NdFeAs(O,H), which possesses the highest Tc among the iron-based superconductors, for SSPD applications. Previously, we reported the fabrication of NdFeAs(O,H) nanostrips with line widths down to 200 nm without a serious decrease in Tc. However, the critical current density (Jc) decreased when the line width was narrower than about 1 µm. Therefore, in the present study, we further optimized the fabrication process to reduce heat generation during Ar-ion dry etching. This improvement resulted in increase of Jc, which was 1.3 MA/cm2 for the narrowest nanostrip that was 540 nm in width, about ten times higher than that of the nanostrip with a similar line width fabricated with the previous process. Further, the results of dark count rate measurements up to 10 K indicated that NdFeAs(O,H)-based SSPDs may be capable of operating at high temperatures.