Different Terahertz Phases of AlGaN/GaN Grating-Gate Plasmonic Crystals

• Main Authors: Sai, P., Dub, M., Korotyeyev, V. V., Filipiak, M., Slowikowski, M., Ivonyak, Yu, But, D. B., Cywinski, G., Knap, W.
• Format: Conference Proceeding
• Language: English
• Subjects: Crystals; Gratings; Logic gates; Plasmons; Resonant frequency; Voltage; Wide band gap semiconductors
• ISSN: 2162-2035
• DOI: 10.1109/IRMMW-THz57677.2023.10299325

We present a comprehensive study of resonant 2D plasmon excitations in the grating-gate plasmonic crystals based on AlGaN/GaN heterostructures. We show that plasmonic crystals are formed and their different phases are electrically controlled by tuning the charge carrier density profile. We conducted both experimental and theoretical investigations of THz 2D plasmon resonances and identified two distinct phases of such plasmonic crystals - the delocalized phase and the localized phase. A continuous transition between these phases of the plasmonic crystal is demonstrated by controlling the gate voltage. Additionally, it was found that the resonant frequency of plasmonic crystal in the localized phase is mainly determined by parameters of the ungated region and unexpectedly depends on the gate voltage. This effect is explained by the specific shrinking of the conductive profile of the 2DEG in the ungated region - edge gate effect. This work represents the first demonstration of an electrically tunable transition between different phases of THz plasmonic crystals, which is a crucial step towards a deeper understanding of THz plasma physics and the development of all-electrically tunable devices for THz optoelectronics.