Sensitivity of Field-Effect Transistor-Based Terahertz Detectors

Abstract

This paper presents an overview of the different methods used for sensitivity (i.e., responsivity and noise equivalent power) determination of state-of-the-art field-effect transistor-based THz detectors/sensors. We point out that the reported result may depend very much on the method used to determine the effective area of the sensor, often leading to discrepancies of up to orders of magnitude. The challenges that arise when selecting a proper method for characterisation are demonstrated using the example of a 2×7 detector array. This array utilises field-effect transistors and monolithically integrated patch antennas at 620 GHz. The directivities of the individual antennas were simulated and determined from the measured angle dependence of the rectified voltage, as a function of tilting in the E- and H-planes. Furthermore, this study shows that the experimentally determined directivity and simulations imply that the part of radiation might still propagate in the substrate, resulting in modification of the sensor effective area. Our work summarises the methods for determining sensitivity which are paving the way towards the unified scientific metrology of FET-based THz sensors, which is important for both researchers competing for records, potential users, and system designers.

Roadmap of Terahertz Imaging 2021

“…Moreover, the availability of both types of components, i.e., sources and detectors, makes it possible to realize allelectronic silicon-based applications spanning from raster-scan imaging [146,157] to near field imaging [158]. It is worth mentioning a very recent study [159] dedicated to the sensitivity issues of nanometric field effect transistors as THz sensors.…”

“…The considered devices are plotted with respect to the emitting power in sources section (left) and the noise equivalent power (NEP) in sensors one (right). Taken data references: Schottky diodes multipliers[87,439] CMOS-based and SiGe-based electronic emitters[62]; CMOS and SiGe detectors parameters[159], parameters of Schottky detectors [440], microbolometers values[167], conventional THz QCL[41]; frequency-difference THz QCLs (FD THz QCLs) parameters-from publications by M. Razeghi[51,52] and M. Belkin's[53] groups. Optoelectronic THz systems (denoted as red solid lines) are attributed for the emitters section only.…”

A Terahertz Detector Based on Double-Channel GaN/AlGaN High Electronic Mobility Transistor

“…The R v can be calculated from the measured Δ U by Equation (10): where S t is the total area of the THz beam spot, S e is the effective area of the detector, P is the total THz radiation power on the beam spot, and factor originates from the rms amplitude in the lock-in amplifier and the Fourier transform of square wave modulated signal. The effective area of the detector can be estimated using the “antenna gain” method [ 24 ]: where G is antenna gain, and λ is the wavelength of the incoming THz wave. The value of G = 1.80 is simulated by HFSS and λ = 952 μm.…”

All-Electronic Emitter-Detector Pairs for 250 GHz in Silicon

“…In current literature, at least six different methods are reported to specify the performance of antenna-coupled THz detectors [ 28 ]. Different possible application scenarios can explain the main reason behind such variety.…”