The sputtering mode diagram (SMD) provides a powerful tool for comprehensive structure engineering of functional films in developing advanced electronic devices, but has not reported due to the complexity of dynamic process and multi-parameters. Here, we report the SMD of superconductor niobium nitride (NbN) films with reactive magnetron sputtering. Poisoned mode, competing mode and metallic mode are drawn by the boundaries identified by the current‒voltage curves of the sputtering system in the SMD, by which the phase structures and electronic properties of the NbN films can be precisely engineered. Typically, 9-nm-thick NbN films grown in the optimal poisoned and competing modes are applied for superconducting nanowire single-photon detectors (SNSPDs). The as-fabricated SNSPDs have flexible performances with saturated quantum efficiency and small kinetic inductance, which enables precise manipulation of the sensitivity and speed from the SMD. This work is also providing guidance for the research of other functional films and electronic devices, which can undoubtedly promote its practical application such as dark matter detection and high-speed quantum communication.

Two-dimensional materials have been demonstrated as promising toolboxes for optoelectronics. Transition metal carbides and nitrides (MXenes), members of an emerging family of two-dimensional materials, have drawn extensive attention in optoelectronics owing to their excellent conductivity and tunable electronic properties. Herein, a photodetector based on the two-dimensional van der Waals heterostructure of Ti₃C₂T_x MXene and a MoS₂ monolayer was constructed to observe the ambipolar photoresponse, which showed a positive photoresponse in the visible spectrum (500–700 nm) and a negative photoresponse at longer wavelengths (700–800 nm). The device exhibited a high negative responsivity of 1.9 A/W and a detectivity of 2.1 × 10¹⁰ Jones under 750 nm light illumination. Detailed experiments demonstrate that the negative photoresponse arises from the heterostructure- induced trap energy level, which confines the excited photoelectrons and leads to an inverse current. This work demonstrates a unique optoelectronic phenomenon in MoS₂/MXene heterostructures and provides valuable insights into the development of new photodetection materials.