Terahertz spectroscopy of plasma waves in high electron mobility transistors

Abstract

We report on systematic measurements of resonant plasma waves oscillations in several gate-length InGaAs high electron mobility transistors (HEMTs) and compare them with numerical results from a specially developed model. A great concern of experiments has been to ensure that HEMTs were not subject to any spurious electronic oscillation that may interfere with the desired plasma-wave spectroscopy excited via a terahertz optical beating. The influence of geometrical HEMTs parameters as well as biasing conditions is then explored extensively owing to many different devices. Plasma resonances up to the terahertz are observed. A numerical approach, based on hydrodynamic equations coupled to a pseudo-two-dimensional Poisson solver, has been developed and is shown to render accurately from experiments. Using a combination of experimental results and numerical simulations all at once, a comprehensive spectroscopy of plasma waves in HEMTs is provided with a deep insight into the physical processes that are involved.

THz Emission Induced by an Optical Beating in Nanometer-Length High-Electron-Mobility Transistors

“…1) repeats essentially that described in detail in Ref. [8]. Additionally, the new setup includes: (i) the system of THz emission detection, and (ii) the sample cooling system.…”

Small-Signal Characterization of FET/HEMT for Terahertz Applications

“…[2] and references therein). Figure 4 illustrates a frequency behavior of the drain--voltage response at the zeroth and first harmonics, U 0 and U 1 , respectively, as functions of the beating frequency of photoexcitation.…”

“…On the other hand, the excitation of 2D plasma waves can be used for THz signal detection which was recently observed experimentally in sub-and near--THz regions (see, e.g. [2] and references therein). Of course, for the analysis of the conditions favourable to realize these effects the knowlegde of the small-signal admittance and impedance of FET/HEMT structures interesting for THz applications is of great importance.…”

“…The aim of this work is just to perform such an investigation through the calculation of the small-signal response of InGaAs HEMTs by using the hydrodynamic approach coupled with a pseudo-2D Poisson equation [2,3].…”

Investigation of 2D plasma resonances in HEMTs by using electro-optical sampling technique

“…Up to now, investigations of eigen 2D plasma waves were carried out mainly in the following directions: (i) experimental investigation of the voltage-tunable spectral behaviour of THz radiation emission from FETs/HEMTs (see, e. g. [2,3] and references therein); (ii) theoretical investigation of spectral behaviour of electronic noise in FET/ HEMT channels [2,4,5]; and (iii) experimental and theoretical investigation of both THz radiation resonant detection and THz re-emission at the beating frequency of two-laser excitation (see, e. g. [6] and references therein).…”