Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering
10
Scopus Publications
Scopus Publications
Electronic and Optical Properties of 2D-TMD/Janus Heterostructures Under the Influence of an Electric Field: First-Principles Calculations Daulet Sergeyev, Ainur Duisenova, Kuanyshbek Shunkeyev Materials, 2025 This work presents the results of a theoretical investigation of the electronic and optical properties of van der Waals Janus nanoheterostructures MoS2/SeMoS and MoSe2/SMoSe, carried out within the framework of density functional theory (DFT) using the generalized gradient approximation (GGA-PBE) together with the Grimme-D3 dispersion correction. The calculated band structures show that both heterostructures possess an indirect bandgap whose magnitude is highly sensitive to an external electric field. In the MoS2–SeMoS system, increasing the applied field leads to a gradual narrowing of the bandgap and a transition to a metallic state at approximately 75 V, whereas in MoSe2–SMoSe, the bandgap first increases (up to 20 V) and then decreases, indicating a nonlinear field-dependent behavior. Analysis of the dielectric function reveals an enhancement of the static dielectric permittivity and a red shift in the absorption spectra with increasing field strength, which can be attributed to charge redistribution and an increased contribution from ionic polarizability. These results demonstrate the possibility of effectively controlling the bandgap width, polarizability, and optical response of Janus nanoheterostructures using an external electric field. This opens up promising prospects for their application in tunable photodetectors, light modulators, valleytronic components, and next-generation optoelectronic systems.
Electronic and Optical Properties of One-Dimensional Van Der Waals Nanodevices Based on MoS2(n,n) and MoSe2(n,n) Nanotubes Daulet Sergeyev, Ainur Duisenova, Kuanyshbek Shunkeyev Crystals, 2024 In this work, the optical and electronic characteristics of MoS2(n,n) and MoSe2(n,n) nanotubes and 1D van der Waals nanoheterostructures based on them are determined from first principles. It is shown that with an increase in the diameters of MoS2(n,n) and MoSe2(n,n) nanotubes, their bandgaps increase (in MoS2(n,n), the gap varies from 0.27 eV to 1.321 eV, and in MoSe2(n,n) from 0.153 eV to 1.216 eV). It was found that with an increase in the diameter of the nanotubes, the static permittivity decreases; van der Waals nanostructures of MoS2(8,8)@MoSe2(16,16) and MoS2(6,6)@MoSe2(14,14) consisting of coaxially compound MoS2(8,8) and MoSe2(16,16), MoS2(6,6) and MoSe2(14,14), respectively, have high static dielectric permittivitiesof 6. 5367 and 3.0756. Such nanoheterostructures offer potential for developing various nanoelectronic devices due to the possibility of effective interaction with an electric field. Studies revealed that the van der Waals nanostructures MoSe2(6,6)@MoS2(14,14) and MoSe2(8,8)@MoS2(16,16) exhibit a semiconductor nature with bandgap widths of 0.174 eV and 0.53 eV, respectively, and MoS2(6,6)@MoSe2(14,14) and MoS2(8,8)@MoSe2(16,16) exhibit metallic properties. Stepped areas of Coulomb origin with a constant period at a voltage of 0.448 V appear on the current–voltage characteristic of the van der Waals nanoheterodevices. It is found that MoSe2(6,6)@MoS2(14,14) and MoSe2(8,8)@MoS2(16,16) nanodevices transmit electric current preferentially in the forward direction due to the formation of a nanoheterojunction between semiconductor nanotubes with different forbidden band values. The fundamental regularities obtained during the study can be useful for the further development of electronic components of nano- and microelectronics.
Simulation of a Single-Electron Device Based on Endohedral Fullerene (KI)@C180 Assel Istlyaup, Ainur Duisenova, Lyudmila Myasnikova, Daulet Sergeyev, Anatoli I. Popov Inorganics, 2023 The progress of modern electronics largely depends on the possible emergence of previously unknown materials in electronic technology. The search for and combination of new materials with extraordinary properties used for the production of new small-sized electronic devices and the improvement of the properties of existing materials due to improved technology for their manufacture and processing, in general, will determine the progress of highly promising electronics. In order to solve the problematic tasks of the miniaturization of electronic components with an increase in the level of connection of integrated circuits, new forms of electronic devices are being created using nanomaterials with controlled electrophysical characteristics. One of the unique properties of fullerene structures is that they can enclose one or several atoms inside their carbon framework. Such structures are usually called endohedral fullerenes. The electronic characteristics of endohedral fullerenes significantly depend on the properties of the encapsulated atom, which makes it possible to control them by choosing the encapsulated atom required by the property. Within the framework of the density functional theory in combination with the method of the nonequilibrium Green’s functions, the features of electron transport in fullerene nanojunctions were considered, which demonstrate “core–shell” nanoobjects, the “core” of which is an alkali halide crystal—KI—and the “shell” of which is an endohedral fullerene C180 located between the gold electrodes (in the nanogap). The values of the total energy and the stability diagram of a single-electron transistor based on endohedral fullerene (KI)@C180 were determined. The dependence of the total energy of fullerene molecules on the charge state is presented. The ranges of the Coulomb blockade, as well as their areas associated with the central Coulomb diamond were calculated.
Model of a single-electron transistor based on endohedral fullerene (Sc3N)@С80 A G Duisenova, D M Sergeyev Journal of Physics Conference Series, 2021 In this work within the framework of the density functional theory and the method of nonequilibrium Green’s functions the dependences of the total energy of molecules C80-SET and (Sc3N)@C80 - SET on their total charge, the dependence of the total energy from the gate voltage and the stability diagram of the single-electron transistor have been determined. It is noted that for transition to switch to on mode (Sc3N)@C80-SET it is necessary to apply the gate voltage in the range from 0.019 ≤ VG ≤ 5.940 with the bias voltage -2.040 ≤ VSD ≤ 2.155 V. Considering that at values of bias voltage equal to –0.381 ≤ VSD ≤ 0.533 V there is no voltage on the substrate (VG = 0 V) and electric current does not flow. It is shown that the total energy at negative values of charge is higher than at positive charges and that the area of the Coulomb rhombus in fullerene with scandium nitride is 5.3 times larger than in “pure” fullerene.
Modeling of electrotransport properties of Li-intercalated graphene film D Sergeyev, A Duisenova, Zh Embergenov Journal of Physics Conference Series, 2021 In this work, within the framework of density functional theory combined with the method of nonequilibrium Green’s functions the density of states, transmission spectrum, current-voltage characteristics, and differential conductivity of Li-intercalated graphene (LiC6) have been determined. It is shown that in the energy range of -1.3÷-1.05 eV the quasiparticle transport through the nanostructure is disable. The features of IV- and dI/dV-characteristics of LiC6 in the form of decreasing of resistance in the range of -0.4÷0.4 V were revealed, and in the interval of 0.4÷1.4 V formation of negative differential resistance area, related to scattering of quasiparticles. It is established, that LiC6 nanodevice has 12÷13 ballistic channels and has the maximum amount of conductance 12÷13G0 , where Go is the conductance quantum.
Computer Simulation of the Electric Transport Properties of the FeSe Monolayer D. Sergeyev, N. Zhanturina, L. Myasnikova, A.I. Popov, A. Duisenova, et al. Latvian Journal of Physics and Technical Sciences, 2020 The paper deals with the model research of electric transport characteristics of stressed and non-stressed FeSe monolayers. Transmission spectra, current-voltage characteristic (CVC) and differential conductivity spectra of two-dimensional FeSe nanostructure have been calculated within the framework of the density functional theory and non-equilibrium Green’s functions (DFT + NEGF). It has been shown that the electrophysical properties depend on the geometry of the sample, the substrate, and the lattice constant. On CVC of non-stressed sample in the range from −1.2 V to −1 and from 1.2 V to 1.4 V, a region of negative differential resistance (NDR) has been observed. NDR is at both signs of the applied voltage due to the symmetry of the nanostructure. d2I/dV2 is used to determine the nature of the electron-phonon interaction and the features of quasiparticle tunnelling in stressed and non-stressed samples. The results obtained can be useful for calculating new elements of 2D nanoelectronics.
