Abstract-Room temperature Si–Ti thermopile THz sensor

• Sofiane Ben Mbarek, 
• Sébastien Euphrasie, 
• Thomas Baron, 
• Laurent Thiery, 
• Pascal Vairac, 
• Danick Briand,
• Jean-Paul Guillet, 
• Laurent Chusseau

http://link.springer.com/article/10.1007/s00542-014-2252-2

In this paper, we present the conception, fabrication and characterization of a thermopile designed to detect terahertz electromagnetic fields at room temperature. The thermopile is made of four doped silicon/titanium thermocouples. The absorber consists of a metallic grid made of titanium, deposited at the same time as the metal part of the thermocouples. The design of the grid is based on a theoretical multilayer model using equivalent resistivity and taking into account small diffraction effects. The grid is deposited on a 2.4 mm × 2.4 mm silicon nitride square membrane. The time constant of the sensor is measured at 0.3 THz to be 10 ms, which is consistent with finite elements simulations. The responsivity is evaluated at 4.8 μV/(W m−2). Due to a large impedance, which leads to a large Johnson noise, the noise equivalent power is 1.5 × 10−6 W Hz−1/2.

Abstract-Traceable terahertz power measurement from 1 THz to 5 THz

Andreas Steiger, Mathias Kehrt, Christian Monte, and Ralf Müller »View Author Affiliations

The metrology institute in Germany, the Physikalisch-Technische Bundesanstalt (PTB), calibrates the spectral responsivity of THz detectors at 2.52 THz traceable to International System of Units. The Terahertz detector calibration facility is equipped with a standard detector calibrated against a cryogenic radiometer at this frequency. In order to extend this service to a broader spectral range in the THz region a new standard detector was developed. This detector is based on a commercial thermopile detector. Its absorber was modified and characterized by spectroscopic methods with respect to its absorptance and reflectance from 1 THz to 5 THz and at the wavelength of a helium-neon laser in the visible spectral range. This offers the possibility of tracing back the THz power responsivity scale to the more accurate responsivity scale in the visible spectral range and thereby to reduce the uncertainty of detector calibrations in the THz range significantly.

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