Plasma oscillations in nanometer field effect transistors are used for detection and generation of electromagnetic radiation of THz frequency. Following first observations of resonant detection in 150 nm gate length GaAs HEMT, we describe recent observations of room temperature detection in nanometer Si MOSFETs, resonant detection in GaN/AlGaN HEMTs and improvement of room temperature detection in GaAs HEMTs due to the drain current. Experiments on spectrally resolved THz emission are described that involve room and liquid helium temperature emission from nanometer GaInAs and GaN HEMTs.

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 1.8-3.1 THz frequency range, which is far above the cutoff frequency of the transistors. The experiments were performed in the temperature range from 10 to 80 K. 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. (c) 2006 American Institute of Physics.

We report on the detection of the sub-THz and THz radiation by silicon FETs and on the voltage tunable emission of terahertz radiation from InGaAs/AlInAs HEMTs with nanoscale gate lengths. The observed photo-response is in agreement with the predictions of the plasma wave response theory. The spectrum of the emitted signal has two peaks. The lower peak is interpreted as resulting from the Dyakonov - Shur instability of the gated two dimensional electron fluid. The emission measurements in a magnetic field show that the threshold voltage remains close to the transistor saturation voltage that increases with magnetic field due to geometric magnetoresistance.

A resonant voltage tuneable radiation (0.4 THz-1.0 THz) from the gated two dimensional electron gas in a 60 nm InGaAs field effect transistor was investigated. We show that (i) the observed emission appears once the drain-to-source voltage, U-DS, exceeds the threshold value, U-TH; (ii) the resonant frequency can be tuned by U,,, in agreement with the current driven plasma instability model of Dyakonov and Shur; (iii) by applying a quantizing magnetic field one increases U-TH linearly with the magnetic field while the evolution of the emission signal is approximately a universal function of (U-DS - U-TH). (c) 2005 WILEY-VCH Verlag GmbH A Co. KGaA, Weinheim.

We report on the experiments about detection of the THz radiation by silicon FETs with nanometer gate lengths. The observed photo-responses measured as a function of the gate voltage are all in agreement with the predictions of the Dyakonov-Shur theory. The plasma wave parameters deduced from the experiments allow us to predict also the possibility of resonant detection in THz range by nanometer size silicon devices. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The influence of the magnetic field on the excitation of plasma waves in InGaAs/AlInAs lattice matched high electron mobility transistors is reported. The threshold source-drain voltage of the excitation of the terahertz emission shifts to higher values under a magnetic field increasing from 0 to 6 T. We show that the main change of the emission threshold in relatively low magnetic fields (smaller than approximately 4 T) is due to the magnetoresistance of the ungated parts of the channel. In higher magnetic fields, the effect of the magnetic field on the gated region of the device becomes important. (C) 2005 American Institute of Physics.