Mid-infrared (MIR) single-photon detection is emerging as an important technology for various applications. Superconducting nanowire single photon detectors (SNSPDs) fabricated with superconducting films with energy gaps of a few meV are natural broadband single-photon detectors. Recently, extending SNSPDs’ operation wavelengths into the MIR region is highly attractive. γ-Nb₄N₃ has a reduced N content and lower energy gap than the commonly used δ-NbN, making SNSPDs based on γ-Nb₄N₃ film more sensitive to low energy photons. We...