THz detection and amplification using plasmonic Field Effect Transistors driven by DC drain currents

TL;DR

This paper presents numerical and theoretical analysis of THz detection and amplification using a current-driven plasmonic FET, revealing how device length and bias influence its response and potential as a THz amplifier and spectrometer.

Contribution

It introduces new equations accounting for channel length dependence and demonstrates the device's ability to amplify THz signals and function as a spectrometer.

Findings

Long-channel TeraFETs have positive response voltage increasing with drain current.

Short-channel TeraFETs exhibit negative response enabling THz amplification.

Resonant modes enhance the negative response and amplification effects.

Abstract

We report on the numerical and theoretical results of sub-THz and THz detection by a current-driven InGaAs/GaAs plasmonic Field-Effect Transistor (TeraFET). New equations are developed to account for the channel length dependence of the drain voltage and saturation current. Numerical simulation results demonstrate that the effect of drain bias current on the source-to-drain response voltage (dU) varies with the device channel length. In a long-channel TeraFET where plasmonic oscillations cannot reach the drain, dU is always positive and rises rapidly with increasing drain current. For a short device in which plasmonic oscillations reach the drain, the current-induced nonuniform electric field leads to a negative response, agreeing with previous observations. At negative dU, the amplitude of the small-signal voltage at the drain side becomes larger than that at the source side. Thus, the device effectively serves as a THz amplifier in this condition. Under the resonant mode, the negative response can be further amplified near the resonant peaks. A new expression of dU is proposed to account for this resonant effect. Based on those expressions, a current-driven TeraFET spectrometer is proposed. The ease of implementation and simplified calibration procedures make it competitive or superior compared with other TeraFET-based spectrometers.