Superconducting nanowire single-photon detectors (SNSPDs) made of ultrathin δ-NbN films have been widely applied in both visible and infrared wavelengths. For mid-infrared (MIR) wavelengths, SNSPDs made of tungsten silicide films with a lower critical temperature were reported up to 9.9 μm wavelength. In this study, we demonstrate the potential of NbN-SNSPDs for use in MIR applications. SNSPDs made of γ-Nb₄N₃ films (critical temperature of 5.1 K for 6.5 nm thick films) instead of δ-NbN films were fabricated. The dependence of the normalized detection efficiency on the bias current indicated a clear trend toward a saturated plateau for wavelengths up to 2145 nm. The calculated cut-off wavelengths indicated the possibility of using γ-Nb₄N₃ SNSPDs for longer MIR wavelengths.

由超薄δ- NbN薄膜制成的超导纳米线单光子探测器（SNSPD）已广泛应用于可见光和红外波长。对于中红外 (MIR) 波长，据报道，由具有较低临界温度的硅化钨薄膜制成的 SNSPD 的波长可达 9.9 μm。在这项研究中，我们展示了 NbN-SNSPD 在 MIR 应用中的潜力。由γ -Nb ₄ N ₃薄膜（6.5 nm 厚薄膜的临界温度为 5.1 K）代替δ制成的SNSPD-NbN 薄膜被制作出来。归一化检测效率对偏置电流的依赖性表明，对于高达 2145 nm 的波长，有明显趋于饱和的趋势。计算出的截止波长表明使用γ -Nb ₄ N ₃ SNSPDs 用于更长的 MIR 波长的可能性。