Plasmonic FET Terahertz Spectrometer

Xueqing Liu,Michael Shur,Trond Ytterdal

doi:10.1109/access.2020.2982275

Abstract

We show that Si MOSFETs, AlGaN/GaN HEMTs, AlGaAs/InGaAs HEMTs, and p-diamond FETs with feature sizes ranging from 20 nm to 130 nm could operate at room temperature as THz spectrometers in the frequency range from 110 GHz to 9.2 THz with different subranges corresponding to the transistors with different features sizes and tunable by the gate bias. The spectrometer uses a symmetrical FET with interchangeable source and drain with the rectified THz voltage between the source and drain being proportional to the sine of the phase shift between the voltages induced by the THz signal between gate-to-drain and gate-to-source. This phase difference could be created by using different antennas for the source-to-gate and drain-to gate contacts or by using a delay line introducing a phase shift or even by manipulating the impinging angle of the two antennas. The spectrometers are simulated using the multi-segment unified charge control model implemented in SPICE and ADS and accounting for the electron inertia effect and the distributed channel resistances, capacitances and Drude inductances.

Highlights

Terahertz (THz) technology applications ranging from spectroscopy and imaging, non-destructive testing, quality control, and communications [1]–[10] require sensitive detectors of THz and sub-THz radiation
A recent proposal is to use TeraFETs as spectrometers and interferometers of THz and sub-THz radiation based on the frequency-dependent THz signal rectification resulting from the phase difference in the THz voltages induced between the source-gate and drain-gate contacts of a single FET detector [16]
Our results show that such Si-based THz spectrometers could operate in the frequency range from 110 GHz to 9.2 THz

Summary

INTRODUCTION

Terahertz (THz) technology applications ranging from spectroscopy and imaging, non-destructive testing, quality control, and communications [1]–[10] require sensitive detectors of THz and sub-THz radiation. A recent proposal is to use TeraFETs as spectrometers and interferometers of THz and sub-THz radiation based on the frequency-dependent THz signal rectification resulting from the phase difference in the THz voltages induced between the source-gate and drain-gate contacts of a single FET detector [16]. The gate voltage, at which the response is zero, depends on the frequency of the impinging THz signal that could be accurately determined. We use the unified charge control THz SPICE model for plasmonic field effect transistors implemented in Verilog-A [17], [18]. It has been validated for FETs in various feature sizes and different material. A more detailed analysis of the process variation effects will be presented

THz SPICE MODEL

CONCLUSION