Silicon Field Effect Transistor as the Nonlinear Detector for Terahertz Autocorellators

Abstract

We demonstrate that the rectifying field effect transistor, biased to the subthreshold regime, in a large signal regime exhibits a super-linear response to the incident terahertz (THz) power. This phenomenon can be exploited in a variety of experiments which exploit a nonlinear response, such as nonlinear autocorrelation measurements, for direct assessment of intrinsic response time using a pump-probe configuration or for indirect calibration of the oscillating voltage amplitude, which is delivered to the device. For these purposes, we employ a broadband bow-tie antenna coupled Si CMOS field-effect-transistor-based THz detector (TeraFET) in a nonlinear autocorrelation experiment performed with picoseconds-scale pulsed THz radiation. We have found that, in a wide range of gate bias (above the threshold voltage Vth=445 mV), the detected signal follows linearly to the emitted THz power. For gate bias below the threshold voltage (at 350 mV and below), the detected signal increases in a super-linear manner. A combination of these response regimes allows for performing nonlinear autocorrelation measurements with a single device and avoiding cryogenic cooling.

Second‐order non‐quasi‐static, compact model of field‐effect transistor revealing terminal rectification beyond their cutoff frequency

“…However, these experimental results are explicable within the results presented in this work, based on terminal rectification. The results presented here also can explain subthreshold THz detection in MOSFETs and HEMTs [22]. In this case, the THz detection was observed despite the absence of channel formation, which can be attributed to terminal rectification.…”

Antenna-Coupled Titanium Microbolometers: Application for Precise Control of Radiation Patterns in Terahertz Time-Domain Systems

“…Moreover, the devices are compact and reliable. As elegant examples can serve employment of CMOS-based field-effect transistors for THz autocorrelators development [ 32 ], coupled-charge device camera to measure spot size of the THz pulse generated by optical rectification in a mosaic organic crystal [ 33 ] or usage of high-speed sampling coupled to CMOS devices for hyperspectral imaging in THz time-domain system [ 34 ].…”

Terahertz Spectroscopy of Thermal Radiation from AlGaN/GaN Heterostructure on Sapphire at Low Temperatures

“…Such systems are of great demand for non-harmful imaging and spectroscopy in biomedical, industrial and security fields [1]. Field-effect transistors (FETs) can operate as a compact detector [2][3][4] or emitter [5][6][7] for THz waves, when incoming radiation creates voltage between transistor channel terminals, or the opposite case where voltage applied along the channel excites THz radiation. For example, resonant THz emission of tunable frequency from 2DEG plasma oscillations can be excited by the strong electric field along HEMT channel [8], while its frequency could be controlled by a gate bias.…”