A. El Fatimy

Resonant and voltage-tunable terahertz detection in InGaAs∕InP nanometer transistors

The authors report on detection of terahertz radiation by high electron mobility nanometer InGaAs∕AlInAs transistors. The photovoltaic type of response was observed at the 1.8–3.1THz frequency range, which is far above the cutoff frequency of the transistors. The experiments were performed in the temperature range from 10to80K. The resonant response was observed and was found to be tunable by the gate voltage. The resonances were interpreted as plasma wave excitations in the gated two-dimensional electron gas. The minimum noise equivalent power was estimated, showing possible application of these transistors in sensing of terahertz radiation.

AlGaN/GaN high electron mobility transistors as a voltage-tunable room temperature terahertz sources

We report on room temperature terahertz generation by a submicron size AlGaN/GaN-based high electron mobility transistors. The emission peak is found to be tunable by the gate voltage between 0.75 and 2.1 THz. Radiation frequencies correspond to the lowest fundamental plasma mode in the gated region of the transistor channel. Emission appears at a certain drain bias in a thresholdlike manner. Observed emission is interpreted as a result of Dyakonov–Shur plasma wave instability in the gated two-dimensional electron gas.

Room temperature tunable detection of subterahertz radiation by plasma waves in nanometer InGaAs transistors

The authors report on the demonstration of room temperature, tunable terahertz detection obtained by 50nm gate length AlGaAs∕InGaAs high electron mobility transistors (HEMTs). They show that the physical mechanism of the detection is related to the plasma waves excited in the transistor channel and that the increasing of the drain current leads to the transformation of the broadband detection to the resonant and tunable one. They also show that the cap layer regions significantly affect the plasma oscillation spectrum in HEMTs by decreasing the resonant plasma frequencies.

Ballistic and pocket limitations of mobility in nanometer Si metal-oxide semiconductor field-effect transistors

Room-temperature magnetoresistance of nanometer bulk Si n-type metal-oxide semiconductor field-effect transistors was measured at magnetic fields up to 10 T. The electron magnetoresistance mobility was determined for transistors with the gate length in 30 to 740 nm range and was shown to decrease with decreasing the gate length. We show that the mobility reduction is caused both by the ballistic and the pocket effect and that for the strong inversion these two effects are of a comparable magnitude.

Plasma wave resonant detection of terahertz radiations by nanometric transistors

We report on resonant terahertz detection by the two-dimensional electron plasma in nanometric InGaAs and GaN transistors. Up to now, the majority of research has been devoted to GaAs-based devices as the most promising from the point of view of the electron mobility. However, resonant detection has been reported only in the sub-THz range. According to the predictions of the Dyakonov–Shur plasma wave detection theory, an increase of the detection frequency can be achieved by reducing the length or increasing the carrier density in the gated region. We demonstrate that the 1THz limit can be overcome by using ultimately short-gate InGaAs and GaN nanotransistors. For the first time the tunability of the resonant signal by the applied gate voltage is demonstrated. We show that the physical mechanism of the detection is related to the plasma waves excited in the transistor channel (Dyakonov–Shur theory). We also show that increasing of the drain-to-source current leads to a transformation of the broadband dete...

Room temperature detection and emission of Terahertz radiation by plasma oscillations in nanometer size transistors

The channel of nanometre field effect transistor can act as a resonant cavity for plasma waves. The frequency of these plasma waves is in the Terahertz range and can be tuned by the gate bias. During the last few years Terahertz detection and emission related to plasma wave instabilities in nanometre size field effect transistors was demonstrated experimentally. In this work we review the recent experimental results on the resonant plasma wave detection and emission at room temperature.

Room-temperature terahertz emission from nanometer field-effect transistors

Generation of THz radiation in nanometer gate length InAlAs/InGaAs and AlGaN/GaN high mobility transistors is observed at room temperature. Spectral analysis of the emitted radiation is presented.

THz communication system based on a THz Quantum Cascade Laser and a Hot Electron Bolometer

We present the experimental study of the direct emission — detection system based on the THz Quantum Cascade Laser as a source and Hot Electron Bolometer (HEB) detector — in view of its application as an optical communication system. We show that the system can efficiently transmit the QCL Terahertz pulses. We estimate the maximal modulation speed of the system to be about several GHz and show that it is limited only by the QCL pulse power supply, detector amplifier and connection line/wires parameters.

Room temperature Terahertz hot electron bolometric detector based on AlGaAs/GaAs two dimensional electron gas

In this paper, we present a hot-electron bolometric detector, which uses the nonlinearities of the heated two-dimensional electron gas medium in AlGaAs/GaAs at room temperature. The cooling process of the electrons is through the phonon-scattering mechanism. The response was measured at the 0.1–0.2 THz frequency range. The response was estimated, showing possible application of these detectors in sensing of Terahertz radiation.

Influence of ballistic and pocket effects on electron mobility in Si MOSFETs

Room temperature magnetoresistance of nanometer bulk Si n-type MOSFETs was measured at magnetic fields up to 10 T. The electron magnetoresistance mobility was determined for transistors with the gate length in 30 nm to 1000 nm range and was shown to decrease with decreasing the gate length. We show that the mobility reduction is caused both by the ballistic motion and the pocket effect and that for the strong inversion the influence of both limitations on the mobility is comparable.