Terahertz Photodetection with Type-II Dirac Fermions in Transition-Metal Ditellurides and Their Heterostructures
Transition-metal dichalcogenides PtTe2, PdTe2, and NiTe2 deserve particular attention, due to the presence of type-II Dirac fermions. As a matter of fact, tilted Dirac cones afford a suitable platform for optoelectronics of dissipation-less carrier-transport, favored by their ultrahigh carrier mobility, and large nonsaturating magnetoresistance. Herein, it is shown that PtTe2, PdTe2, and NiTe2 display high-speed terahertz (THz) detection capability at room temperature, which originates from their peculiar band structure with topologically protected electronic states. Furthermore, photodetectors based on their heterostructures are able to suppress dark current with high-performance detection of THz light. Furthermore, these crystals are stable in air and they can be easily exfoliated in nanosheets by liquid-phase exfoliation, due to the weak interlayer van der Waals bonds. The obtained results clearly establish that the type-II Dirac semimetals based on transition-metal ditellurides have immense research potential for addressing application-oriented issues for remote sensing and telecommunications. © 2021 The Authors. physica status solidi (RRL) Rapid Research Letters published by Wiley-VCH GmbH. ; The support was provided by the State Key Program for Basic Research of China (nos. 2017YFA0305500 and 2018YFA0306204), the National Natural Science Foundation of China (nos. 61521005, 61875217, and 91850208), and the STCSM Grants (no. 1859078100 and 19590780100). Shanghai Municipal Science and Technology Major Project (grant no. 2019SHZDZX01). The project was funded by State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University (KF1809). The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, project no. FEUZ‐2020‐0060). B.G. and A.A. acknowledge funding from Science Education and Research Board (SERB) and Department of Science and Technology (DST), government of India.