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Graphene based field effect transistor for the detection of ammonia J. Appl. Phys. 112, 064304 (2012) Unipolar behavior of asymmetrically doped strained Si0.5Ge0.5 tunneling field-effect transistors Appl. Phys. Lett. 101, 123501 (2012) Efficient physical-thermal model for thermal effects in AlGaN/GaN high electron mobility transistors Appl. Phys. Lett. 101, 122101 (2012) Light/negative bias stress instabilities in indium gallium zinc oxide thin film transistors explained by creation of a double donorThe terahertz absorption spectrum of plasmon modes in a grid-gated double-quantum-well ͑DQW͒ field-effect transistor structure is analyzed theoretically and numerically using a first principles electromagnetic approach and is shown to faithfully reproduce important physical features of recent experimental observations. We find that the essential character of the response-multiple resonances corresponding to spatial harmonics of standing plasmons under the metal grating-is caused by the static spatial modulation of electron density in the channel. Higher order plasmon modes become more optically active as the depth of the electron density modulation in the DQW tends towards unity. The maximum absorbance, at plasma resonance, is shown to be 1/2. Furthermore, the strongest absorption also occurs when the standing plasmon resonance coincides with the fundamental dipole mode of the ungated portion of the channel.

We have solved the problem of diffraction of terahertz radiation on a perfectly conductive gate strip that partially screens a two-dimensional (2D) electron layer located at some distance from the gate. Scattering and absorption spectra of such a structure reveal the fundamental plasma resonance excited under the gate. We have shown that the absorption enhancement factor at plasma resonance may reach very high values (up to 60). However, for narrow gate strips (with the width less than 100nm) the resonant scattering length of such a scatterer is shorter than its resonant absorption length by four orders of magnitude, which means that the gated plasmons in this case weakly couple to the terahertz radiation. We discuss the effects of interaction between plasma oscillations in gated and ungated regions of 2D electron layer and provide a qualitative explanation of the rather intensive terahertz emission from unstable gated plasmons in a 60-nm gate field-effect transistor observed recently.