Broadband and high-speed terahertz wireless sensing via vertical-transport Dirac-source detector.

Abstract

In the realm of wireless sensing, it is envisioned that sensing and communication functionalities will coexist and be fully integrated within a unified system. Future sensing systems thus necessitate detectors capable of operating at higher frequency bands-ranging from millimeter wave to terahertz (THz)-while delivering wider bandwidths, faster response rates, and enhanced functional integration. Dirac-source (DS) detectors use Dirac semimetals as hot-electron sources to capitalize on the low density of states (DOS) near the Dirac point, thereby effectively suppressing the formation of metal-induced gap states. Furthermore, when this architecture incorporates the inherent interlayer vertical electron transport of vertical van der Waals (vdW) heterostructures, it shows great promise for realizing low-power, post-Moore era sensing devices with superior injection and transport efficiencies. Here, we report a DS detector composed of the completely vertical gold/zirconium pentatelluride/graphene/gold structure (Au/ZrTe₅/graphene/Au) heterojunction, which harnesses strong localized fields to achieve high thermionic emission. The detector manifests outstanding performance in terms of remarkable responsivity, exceeds a peak of 1600 V/W from 0.02 to 0.5 THz at room temperature, has a fast response time less than 20 ns, and notably is capable for heterodyne mixing with intermediate frequency (IF) bandwidth larger than ±26.5 gigahertz. Our results not only shed a fresh light on DS dynamics in the terahertz region but also highlight the transformative potential of semimetal electronics for applications in wireless energy harvesting, communication, and imaging.