Abstract
An alternative-grating gated AlGaN/GaN field-effect transistor (FET) is proposed by considering the slit regions to be covered by a highly doped semiconductor acting as supplemental gates. The plasmonic resonant absorption spectra are studied at THz frequencies using the FDTD method. The 2DEGs, under supplemental gates, modulated by a positive voltage, can make the excitation of the higher order plasmon modes under metallic fingers more efficient in comparison to ungated regions in common slit-grating gate transistors. Moreover, the supplemental gates can confine the electric field of dipole oscillation between metallic gate fingers under THz radiation. The competition of the near-field enhancement and screening effect of the supplemental gate fingers results in the intensity of the higher order plasmon resonances being maximized at increased doping concentration. Our results demonstrate the possibility of significant improvement in the excitation of plasmon resonances in FETs for THz detection.
Highlights
IntroductionThe terahertz (THz) response of field-effect transistors (FETs) [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16] with a periodic metal grating gate [5,6,7,8,9,10,11,12,13,14,15,16] has been widely investigated
The absorption spectrum of field-effect hetero-transistors (FEHTs) is calculated with separated 2D electron channels in which the ungated regions are replaced by lateral metal contacts [20,22,23]
The equidistant characteristic of THz absorption peaks is shown in the results of the alternative-grating gates (AGG) as evidence of the excitation of the gated plasmon modes, the peaks have a
Summary
The terahertz (THz) response of field-effect transistors (FETs) [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16] with a periodic metal grating gate [5,6,7,8,9,10,11,12,13,14,15,16] has been widely investigated. Higher order plasmon resonances up to a frequency of 15 THz are obtained and the absorption strength approaches the maximum of 0.25. This effect is the result of the electron liquid in the lateral metal contacts being more “rigid” than that in the 2DEGs. the side metal contacts are more efficient electric vibrators exciting the gated plasmons. The side metal contacts are more efficient electric vibrators exciting the gated plasmons Based on such an idea, we design an alternative-grating gated AlGaN/GaN field-effect transistor by considering the slit regions of the structure to be covered by a highly doped semiconductor acting as supplemental gates. The supplemental gates can be used to make the “ungated” 2DEGs more “rigid” than the 2DEGs under vacuum slits by applying positive voltages
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