Gayduchenko IA, Fedorov GE, Ibragimov RA, Stepanova TS, Gazaliev AS, Vysochanskiy NA, et al. Synthesis of single-walled carbon nanotube networks using monodisperse metallic nanocatalysts encapsulated in reverse micelles. Chem Ind Belgrade. 2016;70(1):1–8.
Abstract: We report on a method of synthesis of single-walled carbon nanotubes percolated networks on silicon dioxide substrates using monodisperse Co and Ni catalyst. The catalytic nanoparticles were obtained by modified method of reverse micelles of bis-(2-ethylhexyl) sulfosuccinate sodium in isooctane solution that provides the nanoparticle size control in range of 1 to 5 nm. The metallic nanoparticles of Ni and Co were characterized using transmission electron microscopy (TEM) and atomic-force microscopy (AFM). Carbon nanotubes were synthesized by chemical vapor deposition of CH4/H2 composition at temperature 1000 °С on catalysts pre-deposited on silicon dioxide substrate. Before temperature treatment during the carbon nanotube synthesis most of the catalyst material agglomerates due to magnetic forces while during the nanotube growth disintegrates into the separate nanoparticles with narrow diameter distribution. The formed nanotube networks were characterized using AFM, scanning electron microscopy (SEM) and Raman spectroscopy. We find that the nanotubes are mainly single-walled carbon nanotubes with high structural perfection up to 200 μm long with diameters from 1.3 to 1.7 nm consistent with catalyst nanoparticles diameter distribution and independent of its material.
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Eletskii AV, Sarychev AK, Boginskaya IA, Bocharov GS, Gaiduchenko IA, Egin MS, et al. Amplification of a Raman scattering signal by carbon nanotubes. Dokl Phys. 2018;63(12):496–8.
Abstract: The effect of Raman scattering (RLS) signal amplification by carbon nanotubes (CNTs) was studied. Single-layered nanotubes were synthesized by the chemical vapor deposition (CVD) method using methane as a carbon-containing gas. The object of study used was water, the Raman spectrum of which is rather well known. Amplification of the Raman scattering signal by several hundred percent was attained in our work. The maximum amplification of a Raman scattering signal was shown to be achieved at an optimal density of nanotubes on a substrate. This effect was due to the scattering and screening of plasmons excited in CNTs by neighboring nanotubes. The amplification mechanism and the possibilities of optimization for this effect were discussed on the basis of the theory of plasmon resonance in carbon nanotubes.
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Gayduchenko I, Kardakova A, Fedorov G, Voronov B, Finkel M, Jiménez D, et al. Response of asymmetric carbon nanotube network devices to sub-terahertz and terahertz radiation. J Appl Phys. 2015;118(19):194303.
Abstract: Demand for efficient terahertz radiation detectors resulted in intensive study of the asymmetric carbon nanostructures as a possible solution for that problem. It was maintained that photothermoelectric effect under certain conditions results in strong response of such devices to terahertz radiation even at room temperature. In this work, we investigate different mechanisms underlying the response of asymmetric carbon nanotube (CNT) based devices to sub-terahertz and terahertz radiation. Our structures are formed with CNT networks instead of individual CNTs so that effects probed are more generic and not caused by peculiarities of an individual nanoscale object. We conclude that the DC voltage response observed in our structures is not only thermal in origin. So called diode-type response caused by asymmetry of the device IV characteristic turns out to be dominant at room temperature. Quantitative analysis provides further routes for the optimization of the device configuration, which may result in appearance of novel terahertz radiation detectors.
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Ryzhii V, Otsuji T, Ryzhii M, Leiman VG, Fedorov G, Goltzman GN, et al. Two-dimensional plasmons in lateral carbon nanotube network structures and their effect on the terahertz radiation detection. J Appl Phys. 2016;120(4):044501 (1 to 13).
Abstract: We consider the carrier transport and plasmonic phenomena in the lateral carbon nanotube (CNT) networks forming the device channel with asymmetric electrodes. One electrode is the Ohmic contact to the CNT network and the other contact is the Schottky contact. These structures can serve as detectors of the terahertz (THz) radiation. We develop the device model for collective response of the lateral CNT networks which comprise a mixture of randomly oriented semiconductor CNTs (s-CNTs) and quasi-metal CNTs (m-CNTs). The proposed model includes the concept of the collective two-dimensional (2D) plasmons in relatively dense networks of randomly oriented CNTs (CNT “felt”) and predicts the detector responsivity spectral characteristics exhibiting sharp resonant peaks at the signal frequencies corresponding to the 2D plasmonic resonances. The detection mechanism is the rectification of the ac current due the nonlinearity of the Schottky contact current-voltage characteristics under the conditions of a strong enhancement of the potential drop at this contact associated with the plasmon excitation. The detector responsivity depends on the fractions of the s- and m-CNTs. The burning of the near-contact regions of the m-CNTs or destruction of these CNTs leads to a marked increase in the responsivity in agreement with our experimental data. The resonant THz detectors with sufficiently dense lateral CNT networks can compete and surpass other THz detectors using plasmonic effects at room temperatures.
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Titova N, Gayduchenko IA, Moskotin MV, Fedorov GF, Goltsman GN. Carbon nanotube based terahertz radiation detectors. In: J. Phys.: Conf. Ser. Vol 1410.; 2019. 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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