Y. M. Meziani

Plasma wave detection of terahertz radiation by silicon field effects transistors: Responsivity and noise equivalent power

Si metal oxide semiconductor field effect transistors (MOSFETs) with the gate lengths of 120–300nm have been studied as room temperature plasma wave detectors of 0.7THz electromagnetic radiation. In agreement with the plasma wave detection theory, the response was found to depend on the gate length and the gate bias. The obtained values of responsivity (⩽200V∕W) and noise equivalent power (⩾10−10W∕Hz0.5) demonstrate the potential of Si MOSFETs as sensitive detectors of terahertz radiation.

Field Effect Transistors for Terahertz Detection: Physics and First Imaging Applications

Resonant frequencies of the two-dimensional plasma in FETs increase with the reduction of the channel dimensions and can reach the THz range for sub-micron gate lengths. Nonlinear properties of the electron plasma in the transistor channel can be used for the detection and mixing of THz frequencies. At cryogenic temperatures resonant and gate voltage tunable detection related to plasma waves resonances is observed. At room temperature, when plasma oscillations are overdamped, the FET can operate as an efficient broadband THz detector. We present the main theoretical and experimental results on THz detection by FETs in the context of their possible application for THz imaging.

Grating-bicoupled plasmon-resonant terahertz emitter fabricated with GaAs-based heterostructure material systems

A grating-bicoupled plasmon-resonant terahertz emitter was fabricated using InGaP∕InGaAs∕GaAs heterostructure material systems. The device structure is based on a high-electron mobility transistor and incorporates doubly interdigitated grating gates that periodically localize the two-dimensional (2D) plasmon in 100nm regions with a submicron interval. Photoexcited electrons, injected to the 2D plasmon cavities, extensively promoted the plasmon instability, resulting in observation of emission of terahertz electromagnetic radiation at room temperature.

Room temperature detection of sub-terahertz radiation in double-grating-gate transistors

Room temperature photovoltaic non-resonant detection by large area double-grating-gate InGaP/InGaAs/GaAs heterostructures was investigated in sub-THz range (0.24 THz). Semi-quantitative estimation of the characteristic detection length combined with self-consistent calculations of the electric fields excited in the structure by incoming terahertz radiation allowed us to interpret quantitatively the results and conclude that this detection takes place mainly in the regions of strong oscillating electric field excited in depleted portions of the channel.

Room temperature terahertz emission from grating coupled two-dimensional plasmons

Room temperature terahertz (far infrared) radiation emission from double grating coupled GaInAs∕AlGaAs∕GaAs heterojunctions is reported. Theoretical calculations of plasmon absorption spectrum are performed using a first principles electromagnetic approach. They correctly reproduce the frequency range and overall shape of the main (broad-band) part of the experimental spectra. The results clearly indicate that important part of the observed room temperature terahertz emission spectra can be due to the radiative decay of hot two-dimensional plasmons in the grating structure.

Emission of terahertz radiation from dual grating gate plasmon-resonant emitters fabricated with InGaP/InGaAs/GaAs material systems

This paper reviews recent advances in our original 2D-plasmon-resonant terahertz emitters. The structure is based on a high-electron-mobility transistor and featured with doubly interdigitated grating gates. The dual grating gates can alternately modulate the 2D electron densities to periodically distribute the plasmonic cavities along the channel, acting as an antenna. The device can emit broadband terahertz radiation even at room temperature from self-oscillating 2D plasmons under the DC-biased conditions. When the device is subjected to laser illumination, photo-generated carriers stimulate the plasma oscillation, resulting in enhancement of the emission. The first sample was fabricated with standard GaAs-based heterostructure material systems, achieving room temperature terahertz emission. The second sample was fabricated in a double-decked HEMT structure in which the grating gate metal layer was replaced with the semiconducting upper-deck 2D electron layer, resulting in enhancement of emission by one order of magnitude.

Room temperature generation of terahertz radiation from a grating-bicoupled plasmon-resonant emitter: Size effect

A doubly interdigitated grating gates structure was incorporated into a GaAs-based high-electron mobility transistor to configure a plasmon-resonant emitter. Two dimensional electrons are then periodically confined in 100nm regions. The devices exhibit a plasma-wave signature under 1.5μm cw laser illumination. Two devices with different geometries have been subjected to an impulsive laser at room temperature. The authors observed clear generation of terahertz radiation from both devices.

Novel Plasmon-Resonant Terahertz-Wave Emitter Using a Double-Decked HEMT Structure

A new plasmon-resonant THz-wave emitter is fabricated and characterized. The heterostructure of the device consists of double-decked high electron mobility transistor (HEMT) and the upper-deck HEMT works as a grating antenna to convert the non-radiative plasmonic wave in the lower-deck HEMT channel to radiative THz electromagnetic wave. This conversion can be done more efficiently than a metal grating antenna. The experimental observed clear evidence of the THz-wave emission from the double-decked HEMT device.

Self Oscillation of the Plasma Waves in a Dual Grating Gates HEMT Device

We report on the photoresponse and emission measurements of the dual grating gates HEMT. An emission of terahertz radiation at room temperature has been detected by a Silicon bolometer. The signal was attributed to the self oscillation of the plasma waves.

Broadband Terahertz Emission from Dual-Grating Gate HEMT's-Mechanism and Emission Spectral Profile

We observed and characterized broadband terahertz emission from our original plasmon-resonant emitter structured by dual-grating gate high electron mobility transistors (HEMTs). The samples are fabricated in two structures: a standard single-heterostructure HEMT with metallic grating gates and a double-decked (DD) HEMT with semiconducting 2-dimensional electron gas (2DEG) grating gates. The mechanism of the broadband emission originated from multi modes of incoherent/coherent plasmon excitations is revealed.