N. Dyakonova

Plasma wave detection of sub-terahertz and terahertz radiation by silicon field-effect transistors

We report on experiments on photoresponse to sub-THz (120GHz) radiation of Si field-effect transistors (FETs) with nanometer and submicron gate lengths at 300K. The observed photoresponse is in agreement with predictions of the Dyakonov–Shur plasma wave detection theory. This is experimental evidence of the plasma wave detection by silicon FETs. The plasma wave parameters deduced from the experiments allow us to predict the nonresonant and resonant detection in THz range by nanometer size silicon devices—operating at room temperature.

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.

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.

Voltage tuneable terahertz emission from a ballistic nanometer InGaAs∕InAlAs transistor

Terahertz emission from InGaAs∕InAlAs lattice-matched high electron mobility transistors was observed. The emission appears in a threshold-like manner when the applied drain-to-source voltage UDS is larger than a threshold value UTH. The spectrum of the emitted signal consists of two maxima. The spectral position of the lower-frequency maximum (around 1 THz) is sensitive to UDS and UGS, while that of the higher frequency one (around 5 THz) is not. The lower-frequency maximum is interpreted as resulting from the Dyakonov–Shur instability of the gated two-dimensional electron fluid, while the higher frequency is supposed to result from current-driven plasma instability in the ungated part of the channel. The experimental results are confirmed by and discussed within Monte Carlo calculations of the high-frequency current noise spectra.

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.

Plasma wave oscillations in nanometer field effect transistors for terahertz detection and emission

We review a few recent results concerning the physics and applications of Field Effect Transistors ( FETs) as Terahertz detectors and emitters. Particulary we stress results concerning dependance of THz detection and emission on high/quantizing magnetic fields and the geometry of the transistor channel.

Nanometer size field effect transistors for terahertz detectors

Nanometer size field effect transistors can operate as efficient resonant or broadband terahertz detectors, mixers, phase shifters and frequency multipliers at frequencies far beyond their fundamental cut-off frequency. This work is an overview of some recent results concerning the application of nanometer scale field effect transistors for the detection of terahertz radiation.

Magnetoresistance characterization of nanometer si metal-oxide-semiconductor transistors

We report on the high-field (up to 10T) magnetoresistance measurements performed on the short (down to 75-nm gate length) n-type Si metal-oxide-semiconductor field-effect transistors. The electron magnetoresistance mobility of these nanometer devices was determined for a wide range of the electron concentration (107–1013cm−2, i.e., from a weak to a strong inversion) and gate length (10μm–75nm). In the case of long samples, the magnetoresistance mobility was compared to the effective mobility obtained by the standard parameter extraction and the split C–V techniques. The results are discussed in terms of the scattering power-law two-dimensional transport analysis. The data clearly indicate a significant decrease of the mobility with the gate length reduction below 100nm.

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.

Current driven resonant plasma wave detection of terahertz radiation: Toward the Dyakonov-Shur instability

The experiments on the dc current influence on resonant terahertz plasma wave detection in InGaAs∕InAlAs multichannel high electron mobility transistors are reported. We observed the line width shrinking when a dc current is applied. We show that this line width decrease is due to the current induced reduction of plasma wave damping and takes place because the current drives the system toward the Dyakonov-Shur plasma wave instability.