Ternary nodal-line semimetal InNbS₂ for highly sensitive broadband terahertz photodetection

Abstract Topological nodal-line semimetals (TNLSs) can be understood as a collection of two-dimensional Dirac Fermions along the line, which endows high mobility and extraordinary electrical transport in all directions near the Dirac points. Furthermore, the band geometry at the Fermi level can be easily modified by external field excitations. These features can bring intriguing properties, such as superconducting, Lifshitz transitions, strong light-matter interaction, and high photoconductivity, supporting low-energy carrier excitations and enhanced optical absorption at terahertz (THz) frequency ranges. Herein, a novel TNLS InNbS 2 -based THz photodetector was fabricated and the photoresponse within 0.02–0.3 THz was explored. A fast response speed of 15.4 μ s, a maximum responsivity ( R I ) of 1.4 A W –1 , and a superb noise equivalent power ( NEP ) of 11.5 pW Hz −1/2 were achieved at 0.11 THz under a bias voltage of 100 mV due to the high photoconductive gain. Meanwhile, the high-resolution THz transmission imaging of a metallic rainbow was carried out to demonstrate the THz imaging functionality. These results explore new avenues for utilizing TNLSs in THz photodetection and establish a basis for the application in the THz field.