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A terahertz (THz) detector based on thermoelectric thin films was simulated using the finite elements method. The thermoelectric circuit consisted of S b and B i 88 S b 12 150-nm films on the mica substrate. S b , B i 88 S b 12 , and mica-substrate properties have been measured experimentally in the THz frequency range. The model of electromagnetic heating was used in order to estimate possible heating of S b - B i 88 S b 12 contact. THz radiation power varied from 1 μ W to 50 mW, and frequency varied in the range from 0.3 to 0.5 THz. The calculations showed a temperature difference of up to 1 K, voltage up to 0.1 mV, and responsivity of several mVW − 1 . The results show that thin S b and B i − S b thermoelectric films can be used for THz radiation detection at room temperatures. [ABSTRACT FROM AUTHOR]

Terahertz (THz) filters and detectors can find a wide application in such fields as: sensing, imaging, security systems, medicine, wireless connection, and detection of substances. Thermoelectric materials are promising basis for THz detectors' development due to their sensitivity to the THz radiation, possibility to be heated under the THz radiation and produce voltage due to Seebeck effect. Thermoelectric thin films of Bi-Sb solid solutions are semimetals/semiconductors with the band gap comparable with THz energy and with high thermoelectric conversion efficiency at room temperature. Detecting film surface can be transformed into a periodic frequency selective surface (FSS) that can operate as a frequency filter and increases the absorption of THz radiation. We report for the first time about the simulation of THz detector based on thermoelectric Bi-Sb thin-filmed frequency-selective surface. We show that such structure can be both detector and frequency filter. Moreover, it was shown that FSS design increases not only a heating due to absorption but a temperature gradient in Bi-Sb film by two orders of magnitude in comparison with continuous films. Local temperature gradients can reach the values of the order of 100 K·mm−1. That opens new perspectives for thin-filmed thermoelectric detectors' efficiency increase. Temperature difference formed due to THz radiation absorption can reach values on the order of 1 degree. Frequency-transient calculations show the power dependence of film temperature on time with characteristic saturation at times around several ms. That points to the perspective of reaching fast response times on such structures. [ABSTRACT FROM AUTHOR]

The terahertz frequency range is promising for solving various practically important problems. However, for the terahertz technology development, there is still a problem with the lack of affordable and effective terahertz devices. One of the main tasks is to search for new materials with high sensitivity to terahertz radiation at room temperature. Bi1−xSbx thin films with various Sb concentrations seem to be suitable for such conditions. In this paper, the terahertz radiation influence onto the properties of thermoelectric Bi1−xSbx 200 nm films was investigated for the first time. The films were obtained by means of thermal evaporation in vacuum. They were affected by terahertz radiation at the frequency of 0.14 terahertz (THz) in the presence of thermal gradient, electric field or without these influences. The temporal dependencies of photoconductivity, temperature difference and voltage drop were measured. The obtained data demonstrate the possibility for practical use of Bi1−xSbx thin films for THz radiation detection. The results of our work promote the usage of these thermoelectric materials, as well as THz radiation detectors based on them, in various areas of modern THz photonics. [ABSTRACT FROM AUTHOR]

Although most types of room-temperature THz detectors involving photothermoelectric (PTE) elements operate in a relatively narrow frequency band due to their antenna-coupled structure, such detectors may be implemented on the basis of non-resonant structures with broadband response due to broadband nature of PTE effect. This work is devoted to improvement of PTE detector sensitivity using serial connection of PTE elements consisting of bismuth-antimony thin films and Cu electrodes. The responsivity of this detector is studied at the frequency of 140 GHz. It is shown that the average voltage produced by PTE detector reaches up to 0.6 mV and is 15 times higher than one produced by continuous film consisting of the same material, while the maximum rate of voltage change is 17 times higher in comparison with continuous film response. Noise equivalent power (NEP) of PTE detector based on Bi 1-x Sb x /Cu branches is equal to 12.6 nW H z − 0. 5 , and noise equivalent temperature difference (NETD) is equal to 4.9 m °C. This detector may be applied in the field of THz and microwave photonics in scanning security systems, THz signal detection in wireless communications, imaging and diagnostics in medicine, food industry and material characterization. • Non-resonant THz PTE detector was implemented using Bi 88 Sb 12 /Cu thermoelectric. • Bi 88 Sb 12 /Cu-based detector consists of 18 series-connected thermoelectric branches. • Average thermo-EMF produced by the detector reaches up to 0.6 mV. • NEP and NETD of the detector are equal to 12.6 nW Hz − 0. 5 and 4.9 m °C. [ABSTRACT FROM AUTHOR]