Terahertz Small-Signal Response of Field-Effect Transistor Channels

Abstract

In this paper, we present an analytical approach for the study of the small-signal response of nanometric field-effect transistor at terahertz frequencies. One-dimensional hydrodynamic equations coupled with a pseudo-two-dimensional Poisson equation are derived at first-order to obtain the small-signal admittance matrix describing the transistor. This matrix is then used to model the loaded device and establish its voltage amplification. The admittances and voltage amplification spectra exhibit sharp resonances associated with the plasma modes of the channel. The influences of the device geometry, operating temperature and connected load are investigated.Index Terms-Nanometric field-effect transistor (FET), resonances, small-signal admittance, terahertz (THz).

Plasma wave resonances in Graphene channels under controlled gate for high frequency applications

“…High resonances in the smallsignal response appeared at frequencies up to 7 THz when a short gate covered the total nano-channel length of the transistor [21,22]. For the THz antenna and detection, the analytical [17,23] and experimental [24,25] studies demonstrate the possibility of amplifying some terahertz frequencies (no more than 2 THz) by the InGaAs HEMTs when the resonant plasma frequency coincides with the frequency of the incoming monochromatic THz radiation. The analysis of HEMTs based on InGaAs material has been described in [14,17] and focus their behavior on terahertz frequencies.…”

“…For the THz antenna and detection, the analytical [17,23] and experimental [24,25] studies demonstrate the possibility of amplifying some terahertz frequencies (no more than 2 THz) by the InGaAs HEMTs when the resonant plasma frequency coincides with the frequency of the incoming monochromatic THz radiation. The analysis of HEMTs based on InGaAs material has been described in [14,17] and focus their behavior on terahertz frequencies. Several high-frequency HEMTs applications, sensing and amplification require the performance of resonances based on strong plasma mode oscillations in the transistor channel.…”

“…Furthermore, High Electron Mobility Transistors (HEMT) have important electrical properties for several terahertz applications, such as detectors, emitters and amplifiers [14][15][16]. The study of HEMTs based on InGaAs material shows the existence of THz plasma-wave oscillations in the channel which leads to the appearance of terahertz resonances in the small-signal admittance spectrum as refered [17][18][19][20]. High resonances in the smallsignal response appeared at frequencies up to 7 THz when a short gate covered the total nano-channel length of the transistor [21,22].…”

“…In this study, analytical calculations are proposed to describe the behavior of HEMTs with graphene channels. The calculations were based on the small-signal model developed for InGaAs HEMTs in [17]. The model was used to determine the response and voltage gain spectra in THz frequencies for different scenarios of Graphene materials (Graphene Monolayer (GML) and Graphene Bilayer (GBL)) and dielectric substrates (H 2 O, Ethanol (160K), HfO 2 and SiO 2 ).…”

A numerical approach to quasi-ballistic transport and plasma oscillations in junctionless nanowire transistors

“…The main idea, based on the shallow-water analogy put forward by Dyakonov and Shur [6][7][8], is to use field-effect transistors with high-mobility channels as nonlinear elements for the resonant detection of incident THz radiation. Moreover, the possibility of plasma instabilities leading to the emission of THz radiation by planar field-effect transistors, as pointed out by Dyakonov and Shur, has resulted in investigations by many groups (e.g., [9][10][11][12][13]). The question arises whether similar plasma instabilities could occur in nanowire or nanotube transistors.…”