Fedorov, G., Gayduchenko, I., Titova, N., Gazaliev, A., Moskotin, M., Kaurova, N., et al. (2018). Carbon nanotube based schottky diodes as uncooled terahertz radiation detectors. Phys. Status Solidi B, 255(1), 1700227 (1 to 6).
Abstract: Despite the intensive development of the terahertz technologies in the last decade, there is still a shortage of efficient room‐temperature radiation detectors. Carbon nanotubes (CNTs) are considered as a very promising material possessing many of the features peculiar for graphene (suppression of backscattering, high mobility, etc.) combined with a bandgap in the carrier spectrum. In this paper, we investigate the possibility to incorporate individual CNTs into devices that are similar to Schottky diodes. The latter is currently used to detect radiation with a frequency up to 50 GHz. We report results obtained with semiconducting (bandgap of about 0.5 eV) and quasi‐metallic (bandgap of few meV) single‐walled carbon nanotubes (SWNTs). Semiconducting CNTs show better performance up to 300 GHz with responsivity up to 100 V W−1, while quasi‐metallic CNTs are shown to operate up to 2.5 THz.
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Saveskul, N. A., Titova, N. A., Baeva, E. M., Semenov, A. V., Lubenchenko, A. V., Saha, S., et al. (2019). Superconductivity behavior in epitaxial TiN films points to surface magnetic disorder. Phys. Rev. Applied, 12(5), 054001.
Abstract: We analyze the evolution of the normal and superconducting properties of epitaxial TiN films, characterized by high Ioffe-Regel parameter values, as a function of the film thickness. As the film thickness decreases, we observe an increase of the residual resistivity, that becomes dominated by diffusive surface scattering for d≤20nm. At the same time, a substantial thickness-dependent reduction of the superconducting critical temperature is observed compared to the bulk TiN value. In such high-quality material films, this effect can be explained by a weak magnetic disorder residing in the surface layer with a characteristic magnetic defect density of approximately 1012cm−2. Our results suggest that surface magnetic disorder is generally present in oxidized TiN films.
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Titova, N., Gayduchenko, I. A., Moskotin, M. V., Fedorov, G. F., & Goltsman, G. N. (2019). Carbon nanotube based terahertz radiation detectors. In J. Phys.: Conf. Ser. (Vol. 1410, 012208 (1 to 5)).
Abstract: In this paper, we study terahertz detectors based on single quasimetallic carbon nanotubes (CNT) with asymmetric contacts and different metal pairs. We demonstrate that, depending on the contact metallization of the device, various detection mechanisms are manifested.
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Saveskul, N. A., Titova, N. A., Baeva, E. M., Semenov, A. V., Lubenchenko, A. V., Saha, S., et al. (2019). Superconductivity behavior in epitaxial TiN films points at surface magnetic disorder. arXiv:1903.05009v3 [cond-mat.mtrl-sci].
Abstract: We analyze the evolution of the normal and superconducting electronic properties in epitaxial TiN films, characterized by high Ioffe-Regel parameter values, as a function of the film thickness. As the film thickness decreases, we observe an increase of in the residual resistivity, which becomes dominated by diffusive surface scattering for d≤20nm. At the same time, a substantial thickness-dependent reduction of the superconducting critical temperature is observed compared to the bulk TiN value. In such a high quality material films, this effect can be explained by a weak magnetic disorder residing in the surface layer with a characteristic magnetic defect density of ∼1012cm−2. Our results suggest that surface magnetic disorder is generally present in oxidized TiN films.
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Tovpeko, N. A., Trifonov, A. V., Semenov, A. V., Antipov, S. V., Kaurova, N. S., Titova, N. A., et al. (2019). Bandwidth performance of a THz normal metal TiN bolometer-mixer. In Proc. 30th Int. Symp. Space Terahertz Technol. (pp. 102–103).
Abstract: We report on the bandwidth performance of the normal metal TiN bolometer-mixer on top of an Al 2 O 3 substrate, which is capable to operate in a wide range of bath temperatures from 77 K – 300 K. The choice of the combination TiN / Al 2 O 3 is related to an advanced heat transport between the film and the substrate in this pair and the sufficient temperature coefficient of resistance. The data were taken at 132.5 – 145.5 GHz with two BWOs as a signal and an LO source. Measurements were taken on TiN films of different thickness starting from 20 nm down to 5 nm coupled into a spiral Au antenna, which improves matching of incoming radiation with the thin TiN fim. Our experiments demonstrate effective heat coupling from a TiN thin film to an Al 2 O 3 substrate (111) boosting gain bandwidth (GB) of TiN bolometer up to 6 GHz for 5 nm thin film. Current results indicate weak temperature dependence of GB on the bath temperature of the TiN bolometer. Theoretical estimations of GB performance meet with experimental data for 5 nm thin TiN films.
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