Field-Effect Transistor Based Detectors for Power Monitoring of THz Quantum Cascade Lasers

Abstract

We report on circuit simulation, modeling, and characterization of field-effect transistor based terahertz (THz) detectors (TeraFETs) with integrated patch antennas for discrete frequencies from 1.3 to 5.7 THz. The devices have been fabricated using a standard 90-nm CMOS technology. Here, we focus in particular on a device showing the highest sensitivity to 4.75-THz radiation and its prospect to be employed for power monitoring of a THz quantum cascade laser used in a heterodyne spectrometer GREAT (German REceiver for Astronomy at Terahertz frequencies). We show that a distributed transmission line based detector model can predict the detector's performance better than a device model provided by the manufacturer. The integrated patch antenna of the TeraFET designed for 4.75 THz has an area of 13 × 13 µm 2 and a distance of 2.2 µm to the ground plane. The modeled radiation efficiency at the target frequency is 76% with a maximum directivity of 5.5, resulting in an effective area of 1750 µm 2. The detector exhibits an area-normalized minimal noise-equivalent power of 404 pW/ √ Hz and a maximum responsivity of 75 V/W. These values represent the state of the art for electronic detectors operating at room-temperature and in this frequency range.

Roadmap of Terahertz Imaging 2021

“…However, improvements in detector design, as well as implementation of detectors in smaller technological nodes, such as 90-nm or 65-nm, resulted in the performance change that is now approaching to the NEP value of 10 pW/ √ Hz [145][146][147]. The exceptional maturity of silicon technologies allow integration of antennas with resonances going deep into the THz frequency range [148,149]. Moreover, detectors with substrate lens demonstrate broadband operation with nearly flat frequency response from 400 GHz up to 1.5 THz [150] and can be used with THz radiation generated employing low-average-power sources, like photomixers [151] or photoswitches [152].…”

Sensitivity of Field-Effect Transistor-Based Terahertz Detectors

“…The dimensions of the metal cup were 254 × 254 µm. More design details and the principal layout schematic can be found in Reference [ 19 ]. In total, we implemented 14 detectors with vertical and horizontal pitch of 279 µm, code-named from to .…”

“…This type of antenna belongs to a well-studied antenna class and has good, predictable radiation properties under front-side illumination. Detectors have been implemented using a similar approach, as detailed in Reference [ 19 ]. The patch antenna was implemented in the top metal layer of the CMOS technological process, with dimensions of 110 × 110 µm (see insert in Figure 2 a).…”

“…The main principle of efficient THz FET detector operations at frequencies highly exceeding the transistor cut-off limit relies on the excitation of damped plasma oscillations in a two-dimensional gas in the transistor channel [ 12 , 13 , 14 , 15 ]. This mechanism was later extended to a device model based on hydrodynamic transport description, in order to account for rectification efficiency and device impedance [ 16 , 17 , 18 , 19 ].…”

A Review of Broadband Low-Cost and High-Gain Low-Terahertz Antennas for Wireless Communications Applications

“…What's more, imaging with higher resolution [8]- [11] can also be achieved by increasing the frequencies and bandwidth of incident waves. With this function, THz imaging is rapidly developed to meet the requirement of some commercial applications, such as THz medical imaging test [12]- [14], atmospheric and environmental monitoring [15]- [17], THz radar [18], [19], national security and anti-terrorism [20]- [23].…”