Field Effect Transistors for Terahertz Detection: Physics and First Imaging Applications

Abstract

22 pages, 12 figures, review paperInternational audienceResonant frequencies of the two-dimensional plasma in FETs increase with the reduction of the channel dimensions and can reach the THz range for sub-micron gate lengths. Nonlinear properties of the electron plasma in the transistor channel can be used for the detection and mixing of THz frequencies. At cryogenic temperatures resonant and gate voltage tunable detection related to plasma waves resonances, is observed. At room temperature, when plasma oscillations are overdamped, the FET can operate as an efficient broadband THz detector. We present the main theoretical and experimental results on THz detection by FETs in the context of their possible application for THz imaging

Wide modulation bandwidth terahertz detection in 130 nm CMOS technology

“…It has also been described as a distributed self mixing resistive mixer [23] and by a lumped element approach for the region where the induced AC current exists [24]. A complete analytical expression valid in all regions of operation of the FET including sub-threshold, linear and saturation as well as the loading effect has been proposed in references [25,26]. Several detector designs for imaging applications employing on-chip antennas coupled to single ended and differential plasma-wave FET have been reported in Silicon and III-V technologies [11][12][13][14][15][16][17][18][19].…”

“…As shown in reference [25], the basic modes of FET based THz detectors can be classified into four groups (Fig. 1a).…”

“…1a). Plasma wave detectors can operate in a resonant or non-resonant, long or short channel modes depending on the channel length, the operating temperature and technology parameters such as electron carrier density and momentum relaxation time (τ ), gate capacitance, and channel conductivity [22,25]. The plasma wave FET can also operate in a high frequency regime for operating frequencies higher than the critical frequency (f c ) defined in Figure 1b.…”

“…The European Physical Journal Applied Physics [25]. To measure the frequency response and the antenna bandwidth, the detector response is then measured within the frequency range of 265 GHz-375 GHz at a fixed gate bias voltage of 0.19 V. As shown in Figure 6a, the absolute responsivity peaks at 292 GHz with a bandwidth of 17 GHz that extends from 286 to 303 GHz.…”

Hydrodynamic modelling of terahertz rectification in AlGaN/GaN high electron mobility transistors

“…The plasmons, relating to a wave-like propagation of charge carriers, can manifest already at microwaves, yet they become increasingly pronounced in the terahertz (THz) frequency range. By now, it has been numerously reported in experimental [2,3] and theoretic [4,5] studies that plasmonic rectification can be employed for efficient detection of THz radiation. Despite such progress, there are many unresolved questions left regarding the validity of predictions from existing hydrodynamic models when applied for the modeling of practical devices (rectifiers or detectors).…”