Low‐Temperature Synthesis of Wafer‐Scale 2D Topological Semimetal NiTe 2 for High‐Efficiency Broadband Photodetection and Imaging

Abstract 2D semimetals have demonstrated tremendous potential in broadband photodetection owing to their unique gapless electronic structure, high carrier mobility, and topological surface states. Nevertheless, complementary metal oxide semiconductor (CMOS)‐compatible low‐temperature synthesis of these materials with large area and precise thickness control remains a critical challenge. In this study, wafer‐scale 2D topological semimetal NiTe 2 films with excellent crystallinity and uniformity are successfully synthesized via an in situ metal‐conversion technique at a low temperature of 300 °C. Based on this, NiTe 2 /Si heterojunction photodetector is constructed, achieving broadband self‐powered photodetection from UV (265 nm) to long‐wave infrared (10.6 µm) at room temperature. The device exhibits exceptional performance metrics, including an ultralow dark current of 3.4 × 10 −14 A, a high responsivity of 682.7 mA W −1 under 980 nm illumination, a specific detectivity of 1.6 × 10 12 Jones, and maintained >10 10 Jones in mid‐ and long‐wavelength infrared (MWIR/LWIR) regions, with a fast response speed of 9.3/40 µs. Notably, the impressive infrared imaging applications are demonstrated in various scenarios of complex pattern recognition, penetration imaging of obscured objects, and solution composition analysis. This work provides a feasible route toward CMOS‐compatible preparation of large‐area 2D semimetals for highly sensitive broadband photodetection and imaging applications.