Despite the considerable effort, fast and highly sensitive photodetection is not widely available at the low-photon-energy range (~meV) of the electromagnetic spectrum, owing to the challenging light funneling into small active areas with efficient conversion into an electrical signal. Here, we provide an alternative strategy by efficiently integrating and manipulating at the nanoscale the optoelectronic properties of topological Dirac semimetal PtSe2 and its van der Waals heterostructures. Explicitly, we realize strong plasmonic antenna coupling to semimetal states near the skin-depth regime (λ/104), featuring colossal photoresponse by in-plane symmetry breaking. The observed spontaneous and polarization-sensitive photocurrent are correlated to strong coupling with the nonequilibrium states in PtSe2 Dirac semimetal, yielding efficient light absorption in the photon range below 1.24 meV with responsivity exceeding ∼0.2 A/W and noise-equivalent power (NEP) less than ~38 pW/Hz0.5, as well as superb ambient stability. Present results pave the way to efficient engineering of a topological semimetal for high-speed and low-energy photon harvesting in areas such as biomedical imaging, remote sensing or security applications.

Terahertz detection has been highly sought to open a range of cutting-edge applications in biomedical, high-speed communications, astronomy, security screening, and military surveillance. Nonetheless, these ideal prospects are hindered by the difficulties in photodetection featuring self-powered operation at room temperature. Here, this challenge is addressed for the first time by synthesizing the high-quality ZrGeSe with extraordinary quantum properties of Dirac nodal-line semimetal. Benefiting from its high mobility and gapless nature, a metal-ZrGeSe-metal photodetector with broken mirror symmetry allows for a high-efficiency photoelectric conversion assisted by the photo-thermoelectric effect. The designed architecture features ultrahigh sensitivity, excellent ambient stability, and an efficient rectified signal even above 0.26 THz. Maximum responsivity larger than 0.11 A W −1 , response time of 8.3 μs, noise equivalent power (NEP) less than 0.15 nW Hz −1/2 , and demonstrative imaging application are all achieved. The superb performances with a lower dark current and NEP less than 15 pW Hz −1/2 are validated through integrating the van der Waals heterostructure. These results open up an appealing perspective to explore the nontrivial topology of Dirac nodal-line semimetal by devising the peculiar device geometry that allows for a novel roadmap to address targeted terahertz application requirements.

Terahertz detectors have potential applications in various fields including security inspection, biomedicine, and noninvasive quality inspection due to their ability to detect terahertz radiation. However, traditional detection materials have reached their bottlenecks due to difficulties in the breakthrough of fundamental principles for terahertz light. In this work, a terahertz detector based on a NiTe2–graphene van der Waals heterostructure has been developed to inhibit the dark current and thermal-agitation noise at room temperature. The hetero-integration of NiTe2 and graphene exhibits enhanced photon-absorption ability and its downconversion into a direct current. The experimental results show that the peak photoresponsivity of our photodetector is 1.31 A W−1 at 0.28 THz, and the corresponding noise equivalent power is 17.56 pW Hz−1/2, which rivals commercially thermal-based photodetectors. Our device has already shown capabilities of large-area imaging, fast speed, and high signal-to-noise ratio, which can be rendered as an important step for exploring topological semimetal optoelectronics.

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The exotic electronic properties of topological semimetals (TSs) have opened new pathways for innovative photonic and optoelectronic devices, especially in the highly pursuit terahertz (THz) band. However, in most cases Dirac fermions lay far above or below the Fermi level, thus hindering their successful exploitation for the low‐energy photonics. Here, low‐energy type‐II Dirac fermions in kitkaite (NiTeSe) for ultrasensitive THz detection through metal‐topological semimetal‐metal heterostructures are exploited. Furthermore, a heterostructure combining two Dirac materials, namely, graphene and NiTeSe, is implemented for a novel photodetector exhibiting a responsivity as high as 1.22 A W−1, with a response time of 0.6 µs, a noise‐equivalent power of 18 pW Hz−0.5, with outstanding stability in the ambient conditions. This work brings to fruition of Dirac fermiology in THz technology, enabling self‐powered, low‐power, room‐temperature, and ultrafast THz detection.