The first demonstration of THz amplification by graphene nanostructures achieved by RIEC-Sendai-Tohoku University team[1,2] raised many fundamental questions like : i) is the graphene really necessary ii) can one scale results obtained on sub-wavelength (μm scale) graphene flakes up to practical size (mm scale) THz amplifier devices. In this work we present recent results on GaN/AlGaN based plasmonic structures obtained in CENTERA -Warsaw, showing that in moderate cryogenic conditions (temperatures ~80K) in many aspects (i.e. carrier density, mobility and optical phonon energy) these structures mimic graphene nanostructures used in the first amplification experiments. The results allow us to identify main challenges/difficulties on the way towards realistic (practical size) plasmonic amplifiers of THz radiation [3,4,5].

ACKNOWLEDGMENTS
Funded by the European Union (ERC ADAVANCED PROJECT -TERAPLASM #101053716). The work was also supported by the “International Research Agendas” Projects CENTERA &CENTERA2 of the Foundation for Polish Science co-financed by the European Union under the European Regional Development Fund (Grant No. MAB/2018/9 for CENTERA & FENG.02.01-IP.05-T004/23) for CENTERA2).

REFERENCES

1. Grating-Gate Graphene Structures 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
   Phys. PhysRevX.10, 031004 (2020); Published: 6 July
2. T. Otsuji, S. A. Boubanga-Tombet, A. Satou, D. Yadav, H. Fukidome, T. Watanabe, T. Suemitsu, A. A. Dubinov, V. V. Popov, W. Knap, V. Kachorovskii, K. Narahara, M. Ryzhii, V. Mitin, M. S. Shur and V. Ryzhii
   Graphene-based plasmonic metamaterial for terahertz laser transistors
   Nanophotonics, vol. 11, no. 9, 2022, 2 February 2022.
3. P. Sai, V. V. Korotyeyev, M. Dub, M. Słowikowski, M. Filipiak, D. B. But, Yu. Ivonyak, M. Sakowicz, Yu. M. Lyaschuk, S. M. Kukhtaruk, G. Cywiński and W. Knap
   Electrical Tuning of Terahertz Plasmonic Crystal Phases
   Phys. Rev. X 13, 041003, Published : 04 October 2023
4. P. Sai, M. Dub, V. Korotyeyev, S. Kukhtaruk, G. Cywinski, and W. Knap
   THz Properties of Grating-Gate Plasmonic Crystals
   Lithuanian Journal of Physics Vol. 63, No. 4, pp. 251–263 (2023), Published : 15 December 2023
5. M. Dub, D. B. But, P. Sai, Yu. Ivonyak, M. Słowikowski, M. Filipiak, G. Cywinski, W. Knap and S. Rumyantsev
   Plasmons in AlGaN/GaN grating-gate structure probing with 300 K background illumination
   AIP Advances 13, 095017 (2023), Published online: 19 September 2023

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