Modeling of antenna-coupled Si MOSFETs in the Terahertz Frequency Range

Abstract: We report on the modeling and experimental characterization of Si CMOS detectors of terahertz radiation based on antenna-coupled field-effect transistors (TeraFETs). The detectors are manufactured using TSMC's 65-nm technology. We apply two models -- the TSMC RF foundry model and our own ADS-HDM -- to simulate the Si CMOS TeraFET performance and compare their predictions with respective experimental data. Both models are implemented in the commercial circuit simulation software Keysight Advanced Design System (ADS). We find that the compact model TSMC RF is capable to predict the detector responsivity and its dependence on frequency and gate voltage with good accuracy up to the highest frequency of 1.2 THz covered in this study. This frequency is well beyond the tool's intended operation range for 5G communications and 110-GHz millimeter wave applications. We demonstrate that our self-developed physics-based ADS-HDM tool, which relies on an extended one-dimensional hydrodynamic transport model and can be adapted readily to other material technologies, has high predictive qualities comparable to those of the foundry model. We use the ADS-HDM to discuss the contribution of diffusive and plasmonic effects to the THz response of Si CMOS TeraFETs, finding that these effects, while becoming more significant with rising frequency, are never dominant. Finally, we estimate that the electrical NEP (perfect power coupling conditions) is on the order of 5 pW/$\sqrt{\rm{Hz}}$ at room-temperature.