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Development of Terahertz Semiconductor Devices Using Novel Nano-Heterostructures and Materials and their ICT Applications



Terahertz coherent electromagnetic waves are expected to explore the potential application fields of future information and communications technologies. We are developing novel, ultra-broadband integrated signal-processing devices/systems operating in the terahertz frequency regime employing novel semiconductor nano-heterostructures and materials. Frequency-tunable plasmon-resonant terahertz emitter and detectors and metamaterial circuits. By using an original dual-grating-gate high-electron mobility transistor (DGG-HEMT) structure with InP-based material systems record-breaking ultrahigh-sensitive detection and coherent monochromatic emission of terahertz radiation have been realized at room temperature. These devices work for terahertz imaging and spectroscopy.
Ultimately-fast terahertz transistors utilizing graphene, carbon-based new material, and compound semiconductor heterojunction material systems.
Graphene-based novel terahertz photonics devices, breaking through the limit on conventional technology. Recently we have succeeded in single-mode terahertz lasing in a dual-gate graphene-channel laser transistor device at 100K. Moreover, we have succeeded in room-temperature terahertz coherent amplification in a dual-grating-gate graphene channel transistor promoted by current-driven graphene Dirac plasmon instability. The obtained maximal gain of 9% is four times as high as the quantum efficiency limit when terahertz photons interact directly with graphene electrons without excitation of graphene plasmons. These will be big steps towards realization of an intense, room-temperature operating graphene plasmonic terahertz laser transistors.

Targeted Application(s)/Industry

By making full use of these world-leading device/circuit technologies, we are exploring future ultra-broadband 6G- and 7G-class wireless communication systems as well as spectroscopic/imaging systems for safety and security. We hope to conduct collaborative research with a willing company for a practical application of this technology in industry.


Research Institute of Electrical Communication

OTSUJI Taiichi , Professor
Doctor of Engineering


Related Information

[1] S. Boubanga-Tombet, W. Knap, D. Yadav, A. Satou, D.B. But, V.V. Popov, I.V. Gorbenko, V. Kachorovskii, and T. Otsuji, "Room temperature amplification of terahertz radiation by grating-gate graphene structures," Phys. Rev. X, vol. 10, iss. 3, pp. 031004-1-19, July 2020.
[2] D. Yadav, G. Tamamushi, T. Watanabe, J. Mitsushio, Y. Tobah, K. Sugawara, A.A. Dubinov, A. Satou, M. Ryzhii, V. Ryzhii, and T. Otsuji, "Terahertz light-emitting graphene-channel transistor toward single-mode lasing," Nanophotonics, vol. 7, iss. 4, pp. 741-752, Apr. 2018.
[3] T. Otsuji, T. Watanabe, S. Boubanga Tombet, A. Satou, W. Knap, V. Popov, M. Ryzhii, and V. Ryzhii, "Emission and detection of terahertz radiation using two-dimensional electrons in III-V semiconductors and graphene," IEEE Trans. Terahertz Sci. Technol., Vol. 3, No. 1, pp. 63-71, Jan. 2013.