. . . . . . . . . .    ANM 2010     3rd International Conference on Advanced Nano Materials     12-15 September 2010 - Agadir, Morocco Back    Abstract ANMM269 STRAINED SILICON MODULATION FET AS NEW SENSOR FOR TERAHERTZ RADIATION Y.M. Meziani 1, E. Diez 1, E. Velazquez 1, K. Fobelets 2, A. Elmoutaouakil 3, and T. Otsuji 3 1/ Salamanca University, Salamanca, Spain 2/ Department of Electrical and Electronic Engineering, Imperial College London, UK 3/ Reseach Institute of Electrical Communication, Tohoku University, Sendai, Japan . Terahertz rays are located in the spectral region 0.1-10 THz (3 mm - 30 µm) between the microwave and the infrared portion of the electromagnetic spectrum. T-rays has the potential to penetrate most common living materials like cloth, papers or plastics. Collective charge density oscillations in two-dimensional electrons systems can be used either for detection and/or emission of terahertz electromagnetic radiations. The resonant frequency of the plasma oscillation is given by the following formulas f≈vp/λ=(e2nsd/mε)1/2×l/L where vp, plasma waves velocity, λ wave length, ns electron density and L gate length. Two important remarks can be deduced: (i) the resonant frequency can reach terahertz range for sub-micron size transistors (ii) the tuning of the resonant frequency can be done by the electron density (i.e. gate bias). When the plasma waves excited by an external electromagnetic radiation the induced ac electric fields can be converted into measurable dc signal via nonlinear conversion mechanism. We report on room temperature non resonant detection of terahertz radiation by using strained-Si modulation doped field effect transistors with 250 nm gate length. A non resonant signal was observed with a maximum around the threshold voltage. The signal was interpreted as related to the plasma waves instability in the channel. The intensity of the signal increases for higher applied drain-to-source bias. A maximum of signal was also observed when the THz light was polarized along the source-to-drain direction. This type of transistors could be a good room temperature sensor based on mature Silicon technology and which could integrate new compact terahertz imaging/spectroscopy systems. . © nanoAC . . . . . . . . . .

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