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

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

Features and Uniqueness
  • 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. We are challenging to develop room-temperature operating coherent and intense laser transistors and fast-response and highly sensitive detectors working for the next-generation beyond-5G terahertz wireless communications as well as safety and security terahertz imaging applications.
  • A. 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.
  • B. 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 of terahertz radiation have been realized at room temperature.
Practical Application

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

Taiichi Otsuji, Professor
Dr. Eng.