An analytical model for terahertz detection in cylindrical surrounding-gate MOSFETs

Guangjin Ma,Chunlai Li,Jin He,Zhiping Zhou,Xiaojuan Ma

doi:10.1063/1.5043450

Abstract

An analytical model for detection of terahertz radiation by plasma wave in cylindrical surrounding-gate (SRG) MOSFETs is presented. In comparison with traditional drain-current models, the rectification response of terahertz signal due to current self-mixing in conducting channel is considered by solving coupled plasma fluid equations using perturbation method. The resulted model is for the first time dipicting detector response in above threshold, near threshold and subthreshold regimes by a single expression valid for both resonant and nonresonant detection schemes. As no fitting parameters is adopted, the model is physical and predicative. Model validity has been extensively verified through numerically solving differential equations with a wide range of incident wave frequencies, channel doping concentrations, device working temperatures, SRG MOSFET geometry parameters as well as incident wave amplitudes. Model applicability to large input terahertz signal has also been discussed. The presented model is convenient for finding the optimum detector design from a multiparameter space. Its great universality will make it a candidate compact model for future terahertz integrated circuit simulation.

Highlights

Terahertz (THz) technology is a field where many potential applications exist.[1,2] In recent years, miniaturization of this technology has been demonstrated in micro-bolometers, quantum cascade lasers, meta-materials, 2D materials,[3,4] nanowires,[5] integrated Schottky diodes and plasmonic nanostructures
A THz electromagnetic wave of frequency f is coupled to the source electrode, exciting a swing voltage of amplitude Ua = 1 mV oscillating at the same frequency
Resonance does not occur for the former case, whereas it occurs for the latter case

Summary

INTRODUCTION

Terahertz (THz) technology is a field where many potential applications exist.[1,2] In recent years, miniaturization of this technology has been demonstrated in micro-bolometers, quantum cascade lasers, meta-materials, 2D materials,[3,4] nanowires,[5] integrated Schottky diodes and plasmonic nanostructures. The first theory on detection of THz radiation in field effect transistors (FETs) was invented more than 20 years ago,[6] which handles both the nonresonant detection[14] and the resonant detection[15] schemes but only applies to the far above threshold regime In complementary to this theory, a following model for nonresonant detection was proposed by Knap et al.,[16] in which gate leakage current is found important for detector performance in subthreshold regime. Using a numerical method to handle electron fluid dynamics by directly solving partial differential equations[18] is a universal solution It generally needs much heavier computation load and is not expected to be suitable for future THz circuit simulation.

MODEL DERIVATION

RESULTS AND DISCUSSION

CONCLUSIONS