Effect of photogenerated electrons on the terahertz plasma-wave resonance in HEMT's under interband photoexcitation

Mitsuhiro Hanabe, Taiichi Otsuji, Victor Ryzhii

Research output: Contribution to journalConference articlepeer-review


Two-dimensional (2-D) electron plasma in a submicron channel of a high-electron mobility transistor (HEMT) can make resonant oscillation in the terahertz range. The gate bias potential Vgs can control the resonant frequency fr, which offers the possibility of tunable coherent terahertz oscillators. The terahertz plasma-wave excitation can be performed by means of interband photoexcitation in a manner of laser-photomixed difference-frequency (Δf) generation. The 2-D electron plasma in the electron channel is excited by the terahertz Δf component of the photoexcited carriers. Since the photoelectrons perturb the surface density of 2-D electrons, strong photoexcitation dynamically modulates the fr, resulting in considerable resonant-spectral broadening. This effect was modeled analytically in the 2-D plasma hydrodynamic equation. The modulation depth of the density of 2-D electrons by the photoelectrons deeply relates to the resonant intensity and fr. In order to validate the analytical calculation, the plasma-wave resonance was experimentally observed for a 0.15-μm gate-length InGaP/InGaAs/GaAs pseudomorphic HEMT in the terahertz range. At the modulation depth of 30%, the resonance was clearly observed with a double peak (the peak at 1.9/5.8 THz corresponding to the fundamental /third harmonic resonance). On the contrary, under a low modulation depth condition, the plasma resonant intensity decreased. Observed resonant frequencies support the analytical calculation.

Original languageEnglish
Pages (from-to)218-225
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 2004 Dec 20
Externally publishedYes
EventMicrowave and Terahertz Photonics - Strasbourg, France
Duration: 2004 Apr 292004 Apr 30


  • HEMT
  • Interband photoexcitation
  • Photogenerated electrons
  • Plasma-wave resonance
  • Terahertz

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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