V.V. Shunaev – Ph.D.(Phys.-Math.), Senior Lecturer, 

Department of Radiotechnique and Electrodynamics, Saratov State University named after N.G. Chernyshevsky E-mail: vshunaev@list.ru

O.E. Glukhova – Dr.Sc.(Phys.-Math.), Professor, Head of the Department of Radiotechnique and Electrodynamics,  Saratov State University named after N.G. Chernyshevsky E-mail: GlukhovaOE@info.sgu.ru

Photodetectors of atomic thickness on the base of carbon nanostructures consume little energy and don’t require cooling. A prospect material for such photodetectors may be T-junctions of carbon nanotube (CNTs) which optical properties haven’t been studied yet. In this regard, the aim of this work was to calculate the real part of the optical conductivity of films composed of T-junctions. The diameter of the CNT was in the range of 1.4…1.8 nm. The atomic model of T-junctions was built by originally developed software, then its coordinates were refined by the SCC DFTB 2 method. In the place of the CNT’s T-contact it was observed defects in the form of pentagons and septagons. For the built atomic models of T-junctions and the corresponding CNTs the real part of the optical conductivity was calculated by the Kubo–Greenwood formula. It was established that armchair CNTs demonstrate optical conductivity in the range of ultraviolet and visible radiation, while optical conductivity for T-compounds formed by nanotubes of the same type is observed in addition in the near and middle infrared ranges. Herewith the optical conductivity of T-compounds in the range of 0.1…0.46 µm increases in 2…5.5 times depending on the chirality of the CNT, while the peaks of optical conductivity observed in this range are preserved. The number of peaks in the range of 0.1…0.46 μm increases with growth of CNTs chirality. For CNTs of zigzag type the optical conductivity is observed at the frequencies of 0.1…4 μm (in the ultraviolet, visible, and near infrared ranges). It was found that in the range of 0.1…0.6 μm the real part of the optical conductivity of T-compounds exceeds the real part of the optical conductivity of single-walled CNTs in 2…7 times depending on the CNT’s diameter. The results confirm the feasibility T-compounds application as sensitive elements for photodetectors.

1. He X., Léonard F., Kono J. Uncooled Carbon Nanotube Photodetectors. Advanced Optical Materials. 2015. V. 3. № 8. P. 989−1011.
2. Nanot S., Cummings A.W., Pint C.L., Ikeuchi A., Akiho T., Sueoka K., Hauge R.H., Léonard F., Kono J. Broadband, PolarizationSensitive Photodetector Based on Optically-Thick Films of Macroscopically Long, Dense, and Aligned Carbon Nanotubes. Scientific Reports. 2013. V. 3: 1335.
3. Chiu P.-W. Carbon Nanotube Nanocontact in T-junction Structures. Applied Physics Letters. 2007. V. 91. P. 102109.
4. Chiu P.-W. Carbon Nanotube T Junctions: Formation and Properties. Journal of Nanoscience and Nanotechnology. 2008. V. 8. P. 88−98.
5. Glukhova O.E., Savostyanov G.V., Slepchenkov M.M. Svidetelstvo o gosudarstvennoi registratsii programmy dlya EVM № 2018661600 «Programmnyi generator atomnoi struktury grafenovykh nanoblisterov Blistmaker». Zaregistrirovano v Reestre programm dlya EVM 03.09.2018 (data obrashcheniya 26.03.2019). (in Russian)
6. Elstner M., Porezag D., Jungnickel G. Self-consistent-charge Density-functional Tight-Binding Method for Simulations of Complex Materials Properties. Physical Review B. 1998. V. 56. P. 72607.