High intensity study of THz detectors based on field effect transistors

TL;DR

This study investigates the terahertz power dependence of field effect transistor photoresponse, revealing linear behavior at low intensities and saturation at high intensities, supported by a developed theoretical model.

Contribution

The paper introduces a comprehensive theoretical model explaining high-intensity photoresponse saturation in THz FETs, supported by experimental validation across various devices.

Findings

Photoresponse increases linearly up to kW/cm^2

Saturation occurs at several kW/cm^2 due to drain photocurrent saturation

Dynamic range exceeds six orders of magnitude in power density

Abstract

Terahertz power dependence of the photoresponse of field effect transistors, operating at frequencies from 0.1 to 3 THz for incident radiation power density up to 100 kW/cm^2 was studied for Si metal-oxide-semiconductor field-effect transistors and InGaAs high electron mobility transistors. The photoresponse increased linearly with increasing radiation power up to kW/cm^2 range. The saturation of the photoresponse was observed for all investigated field effect transistors for intensities above several kW/cm^2. The observed signal saturation is explained by drain photocurrent saturation similar to saturation in direct currents output characteristics. The theoretical model of terahertz field effect transistor photoresponse at high intensity was developed. The model explains quantitatively experimental data both in linear and nonlinear (saturation) range. Our results show that dynamic range of field effect transistors is very high and can extend over more than six orderd of magnitudes of power densities (from 0.5 mW/cm^2 to 5 kW/cm^2).