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.

The injection of nonequilibrium carriers in a paramagnetic diluted magnetic semiconductor in the presence of magnetic field may induce a spontaneous magnetization patterning. This phenomenon is studied in CdMnTe quantum wells using time resolved Kerr rotation experiments and the model based on the coupled rate equations for interacting electron and magnetic ion spins is developed.

We report on tunable terahertz resonant detection of two 1.55 µm cw-lasers beating by plasma waves in AlGaAs/InGaAs/InP high-electron-mobility transistor. We show that the fundamental plasma resonant frequency and its odd harmonics can be tuned with the applied gate-voltage in the range 75–490 GHz. The observed frequency dependence on gate-bias is found to be in good agreement with the theoretical plasma waves dispersion law.

Transverse electron and hole spin relaxation times were measured in both parts of a generic spintronic structure device consisting of two thin layers: diluted magnetic Cd0.96Mn0.04Te (spin aligner) and a layer non-magnetic CdTe (spin accumulator). By using time-resolved magnetoptical Kerr rotation as a fast time-resolved magnetization probe, we find that the carriers in Cd0.96Mn0.04Te lose their initial spin coherence within similar to 1ps. The undoped spin accumulator is characterized by relatively long electron spin relaxation time that of the order of several hundreds ps.

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.