Spectral Narrowing Effect of a Novel Super-Grating Dual-Gate Structure for Plasmon-Resonant Terahertz Emitter

Takuya NISHIMURA  Nobuhiro MAGOME  HyunChul KANG  Taiichi OTSUJI 

Publication
IEICE TRANSACTIONS on Electronics  Vol.E92-C  No.5  pp.696-701
Publication Date: 2009/05/01
Online ISSN: 1745-1353
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Fundamentals and Applications of Advanced Semiconductor Devices)
Category: 
Keyword: 
terahertz,  plasmon resonance,  emitter,  dispersion control,  grating dimension, 

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Summary: 
We have proposed a terahertz (THz) emitter utilizing two-dimensional plasmons (2DPs) in a super-grating dual-gate (SGG) high electron mobility transistor (HEMT). The plasmon under each grating gate has a unique feature that its resonant frequency is determined by the plasma-wave velocity over the gate length. Since the drain bias voltage causes a linear potential slope from the source to drain area, the sheet electron densities in periodically distributed 2DP cavities are dispersed. As a result, all the resonant frequencies are dispersed and undesirable spectral broadening occurs. A SGG structure can compensate for the sheet electron density distribution by modulating the grating dimension. The finite difference time domain simulation confirms its spectral narrowing effect. Within a wide detuning range for the gate and drain bias voltages giving a frequency shifting of 0.5 THz from an optimum condition, the SGG structure can preserve the spectral narrowing effect.