Modeling and Analysis of Plasmonic Terahertz Wave Detector Based on Field Effect Transistor

Abstract

I propose accurate analysis and novel model of the nonresonant plasmonic terahertz (THz) wave detector based on the silicon (Si) field effect transistor (FET) with a technology computer-aided design (TCAD) platform and SPICE simulation. By introducing a quasi-plasma two-dimensional electron gas (2DEG) in the channel of the FET, the physical behavior of the plasma wave has been modeled with the TCAD platform. For accurate analysis of the modulation and propagation of the channel electron density as the plasma wave, I have characterized the quasi-plasma 2DEG model with two key parameters, such as quasi-plasma 2DEG length (lQP) and density (NQP). The lQP and NQP is defined exactly as extracting the average point of the electron density by using the normalization method. Through the quasi-plasma 2DEG modeling, I investigate the performance enhancement of the plasmonic terahertz wave detector based on Si FET according to scaling down the gate oxide thickness (tox), which is a significant parameter of FET-based plasmonic terahertz detector for the channel electron density modulation. By scaling down tox, the responsivity (Rv) and noise equivalent power (NEP), which are the important performance metrics of the THz wave detector, have been enhanced. In addition, I report the new NQS compact model for MOSFET-based THz wave detector using SPICE simulation. Because the FETs are intensively considered for THz detector due to their performance and applicability, it is essential to describe the physical behaviors of FET in the THz regime with non-quasi-static (NQS) analysis. However, most of the NQS MOSFET models (e.g., Elmore model) have the complexity of the formulation and fail to describe the device physics for the accurate analysis of fast switching and high-frequency operation. In this work, I have proposed novel NQS compact model of MOSFET, which is applicable for transient simulation of the plasmonic THz detectors. The new SPICE NQS model has been verified by comparing with TCAD device simulation as reference of the complete numerical NQS simulation. For simulation of MOSFET-based plasmonic THz detector with SPICE, I demonstrate the model validity by extracting the photoresponse simulation as the function of the gate voltage at 0.2 THz with the peak point in the sub-threshold region. The proposed novel methodologies will provide the advanced physical analysis and efficient structural design for developing the nonresonant plasmonic terahertz detectors operating in THz regime.