Ermachikhin, Alexander Valeryevich

PhD in Physics and Mathematics
🤝
Publications
46
Citations
80
h-index
5
Semenov A.R., Litvinov V.G., Kholomina T.A., Ermachikhin A.V., Rybin N.B.
2023-10-18 citations by CoLab: 1 Abstract
The results of an experimental study of the surface morphology of zinc-oxide films and the electrical properties of structures based on a single-crystal Si/microcrystalline ZnO heterojunction are presented. An analysis of the structure of the zinc-oxide films grown in argon and oxygen atmospheres is carried out, and the size distribution of nanofibers grown on its surface is obtained. The capacitance–voltage characteristics of In/ZnO/n-Si/Al and Au/ZnO/n-Si/Al heterostructures are simulated. On the basis of calculations and comparison of the experimental and simulated dependences, the concentration of free charge carriers in the sample and the position of the Fermi level are determined, the presence of a fixed charge in the system is revealed, and the density of surface states is found based on the ratio of the voltage applied to the system and the surface potential at the interface between layers. The value of the built-in surface charge is calculated. The relationship between the material of the upper contacts and the capacitance–voltage and current–voltage characteristics of the system is studied. The resistance of the formed zinc-oxide films is calculated. The prevailing charge-transfer mechanisms are discussed. An empirical dependence of the surface potential of silicon on the voltage applied to the structure is revealed. The effect of technological modes for obtaining zinc-oxide films synthesized by spray pyrolysis on the surface structure, effective capacitance of the structure, density of electronic states, and processes of charge-carrier transfer in samples under the action of an electric field is analyzed.
Ermachikhin A.V.
2022-12-26 citations by CoLab: 0 Abstract
In this paper a measuring analytical system for low-frequency noise spectroscopy is presented. The measuring system is adapted for the automated study of low-frequency noise spectra in electronic elements, components and semiconductor materials and structures. A distinctive feature of the proposed measuring system is an automated complex local and precise study of the dependence of the low-frequency noise spectra in the sample on electrical voltage and temperature. The frequency range is 0.001-10000 Hz, DC bias range is 0-50 V and the temperature range is 7-500 К. The measuring system is adapted for use with an atomic force microscope for local measurements of electronic materials and structures noise characteristics. The measuring system makes it possible to obtain a larger amount of experimental data, which makes it possible to draw comprehensive conclusions about the mechanisms and causes of noise generation in the test sample. The results of testing the operation of the measuring system are given as an example of the Schottky diode-like structure study.
Ermachikhin A.V., Vorobyov Y.V., Trusov E.P.
2022-02-01 citations by CoLab: 0 Abstract
A setup for measuring the spectral dispersion of the external quantum efficiency in a wide temperature range is described. The setup is capable of monitoring variations in the luminous flux power and making corrections in calculations of the quantum efficiency. The absence of the second optical channel for monitoring variations in the light power is a distinctive feature of the setup. Owing to this feature, it is possible to eliminate mobile parts in the setup, which simplifies the design and does not require synchronizing devices.
Semenov A.R., Kholomina T.A., Litvinov V.G., Ermachikhin A.V.
2021-12-30 citations by CoLab: 0
Ermachikhin A.V., Vorobyov Y.V., Trusov E.P., Litvinov V.G.
2021-11-01 citations by CoLab: 0 PDF Abstract
Abstract The effect of solar cell fragment annealing on its noise characteristics is shown. The calculated difference in relaxation times arising from the change in noise after annealing was 30%. Measurements of noise characteristics in the dark and under illumination with a red laser with different radiation power were carried out. Close to linear dependences of noise power reduction with increasing radiation power were obtained.
Vorobyov Y.V., Ermachikhin A.V., Trusov E.P.
2021-07-01 citations by CoLab: 0 PDF Abstract
Abstract The non-Arrhenius behaviour of conductivity of phase-change materials is analysed in terms of the statistical shift of Fermi level. To show this connection, a simplified model for the density of states in a phase-change material is proposed to simulate the temperature dependence of the Fermi level. Comparison of the temperature dependence of conductivity of Ge2Sb2Te5 with the simulation results allowed estimating the position of defect levels in the bandgap.
Vorobyov Y., Ermachikhin A., Yakubov A., Trusov E., Fedyanina M., Lazarenko P., Kozyukhin S.
2021-05-25 citations by CoLab: 6 Abstract
Abstract The non-Arrhenius behaviour of Ge2Sb2Te5 conductivity is attributed to the non-linear temperature dependence of the Fermi level, assuming extended state conduction by free holes. The temperature-dependent Fermi level is shown to alter values of activation energy and prefactor for conductivity so that their exact determination becomes impossible using the conductivity data alone. However, if one assumes the temperature dependence of the Fermi level to be a parabolic function. Then, two of three model parameters can be retrieved; to obtain the third parameter one has to make an assumption about the value of prefactor for conductivity. Applying the proposed analysis scheme to Ge2Sb2Te5, reasonable values of Fermi level position are obtained and the change of Fermi level as a result of resistance drift phenomenon is demonstrated.
Rudenko M., Gaponenko N., Litvinov V., Ermachikhin A., Chubenko E., Borisenko V., Mukhin N., Radyush Y., Tumarkin A., Gagarin A.
Materials Q2 Q2 Open Access
2020-12-17 citations by CoLab: 8 PDF Abstract
Eu3+ doped porous nanostructured SrTiO3 films and powder fabricated by sol-gel route without using any precursor template are characterized by different morphology and phase composition. The films and the power show red and yellow luminescence with the most intensive photoluminescence (PL) bands at 612 nm and 588 nm, respectively. Raman, secondary ion mass spectrometry (SIMS), and X-ray diffraction (XRD) analysis of undoped nanostructured porous SrTiO3 films showed the presence of TiO2, SrO, and SrTiO3 phases and their components. The undoped porous SrTiO3 films are photosensitive and demonstrate resistive switching. The capacitance-voltage hysteresis loops with the width of about 6 V in the frequency range of 2 kHz—2 MHz were observed.
Ermachikhin A.V., Vorobyov Y.V., Maslov A.D., Trusov E.P., Litvinov V.G.
2020-10-09 citations by CoLab: 3 Abstract
It is shown that the use of both sides of solar cells created with the heterojunction technology makes possible an increase in the solar-cell efficiency. The difference in illumination of the front and back sides is associated with transformation of the blue part of the spectrum, which is shown by the example of the spectral dispersion of the quantum efficiency. The average difference between the quantum efficiency for both sides is ~11%. The short-circuit current density with the power of the solar spectrum at sea level from 400 to 1100 nm is 36.3 mA/cm2 for the front side and 32.7 mA/cm2 for the back side. The decrease amounts to 9.7%.
Vorobyov Y.V., Yakubov A.O., Ermachikhin A.V.
Abstract Results of studies of conductivity activation energy and its evolution during the aging process are presented for the common phase change material Ge2Sb2Te5. The evolution of temperature dependence of conductivity during quasi-isothermal annealing are interpreted in the framework of simple Arrhenius model as the change of two corresponding parameters: activation energy and pre-exponential factor. It is shown, that the change in resistivity of the Ge2Sb2Te5 during aging is attributed to the simultaneous change of both parameters of the Arrhenius equation, that is, activation energy and pre-exponential factor. Temperature dependencies of those parameters are shown as well, and the Meyer-Neldel rule for conductivity of Ge2Sb2Te5 is tested on the basis of the obtained data.
Vorobyov Y., Lazarenko P., Sherchenkov A., Vishnyakov N., Ermachikhin A., Kozyukhin S.
2020-05-29 citations by CoLab: 2 Abstract
A mathematical model of the crystallization process in a thin film is presented with the purpose to overcome the limitations of Kolmogorov-Johnson-Mehl-Avrami theory regarding finite-size systems. Two ways of nucleation are taken into account: at the film boundaries and in the bulk. The solution is obtained in terms of crystallization probability, which is the probability of a point inside the film to be included in the crystal at a given moment of time. It is shown that the characteristic feature of crystallization in finite-size systems is a non-uniform distribution of crystalline fraction.
Tregulov V.V., Litvinov V.G., Ermachikhin A.V., Maslov A.D.
13th International Conference ELEKTRO 2020, ELEKTRO 2020 - Proceedings
2020-05-01 citations by CoLab: 1 Abstract
In this paper we investigated n+-p-junction silicon solar cells with antireflection por-Si film, formed on the front surface by anodic electrochemical etching. Photocurrent of the samples is measured. Also we used current deep level transient spectroscopy method. We found that defects with deep levels, appeared during formation of por-Si layer strongly affect photocurrent spectra of the cells due to the amplification of recombination of photogenerated charge carriers.
Maslov A.D., Litvinov V.G., Ermachikhin A.V., Vishnyakov N.V., Gudzev V.V., Vikhrov S.P.
13th International Conference ELEKTRO 2020, ELEKTRO 2020 - Proceedings
2020-05-01 citations by CoLab: 0 Abstract
In this paper we present results of DLTS investigating HIT solar cells. Analysis of DLTS spectra gave deep level activation energies and concentrations. However this method hardly allows to find spatial localization of these defect states. Therefore here we developed a method to find separated values of recombination rates corresponding to different spatial regions: a-Si layers, interfaces, depletion region and quasineutral base. We quantity found that recombination in the depletion region and at the interfaces strongly dominate and affect efficiency of the cell. Here we show that this technique is useful for interpretation of DLTS data and investigation of recombination processes in HIT solar cells.
Semenov A.R., Golovanova M.V., Litvinov V.G., Gromov D.G., Oleynik S.P., Kholomina T.A., Ermachikhin A.V.
2019-01-01 citations by CoLab: 1
Tregulov V.V., Litvinov V.G., Ermachikhin A.V.
2019-05-01 citations by CoLab: 0 Abstract
We have studied experimental samples of photoelectric transducers with an n+–p junction based on a silicon single crystal and an antireflection porous silicon (por-Si) film formed by color chemical etching in a HF : KMnO4 : C2H5OH etcher. It is shown that for KMnO4 oxidant concentrations of 0.025 and 0.040 M, the por-Si film growth time at which the maximal efficiency of the photoelectric transducer is reached can be substantially increased as compared to that attained using anode electrochemical etching. For investigating the current transmission mechanisms, we have measured the temperature dependence of forward- and backward-bias current–voltage branches. The existence of several current transmission mechanisms has been established. It is found that traps with activation energy distributed in a continuous range of values considerably affect the current transmission.
Kumar A., Tomer S., Vandana, Fix T., Dutta M., Srivastava S.K., Prathap P.
2024-09-25 citations by CoLab: 1 Abstract
Abstract The performance of MoO x based devices is highly influenced by the presence of oxygen vacancies and the trap density at the oxide-semiconductor interface. This paper presents a detailed investigation of the surface states present at the MoO x /c-Si interface through capacitance and conductance methods. Thin films of MoO x were deposited on n-Si using DC reactive sputtering of Mo under varying oxygen flow rates and studied the modulation of metal-insulator-semiconductor (MIS) device parameters using appropriate analysis methods. The capacitance-voltage (CV) analysis reveals the formation of nearly dielectric films at an intermediate oxygen flow rate of 15 sccm, exhibiting a dielectric constant of 24 and negative fixed charges of approximately 1.81 × 1012 cm−2. The work function evaluated from the Kelvin probe measurements was found to be a maximum of 5.08 eV for the films deposited at an intermediate oxygen flow rate of 15 sccm. Furthermore, admittance analysis was performed on all the films to determine the loss mechanism in different regions, ranging from inversion to accumulation. Parallel conductance for different bias conditions was studied and observed the domination of oxide traps at higher oxygen flow rates (>20 sccm). Investigations of deep level defects were performed using deep level transient spectroscopy (DLTS) in the temperature range of 100 K–475 K, along with the C-V measurements. A transition in C-V behavior is observed below room temperature, implying that the minority carrier response time is controlled by generation-recombination at low temperatures and by diffusion at high temperatures. X-ray photoelectron spectroscopy (XPS) measurements showed that the films are sub-stoichiometric with the dominant oxidation state of Mo+6. The results are discussed and presented in detail.
Korir B.K., Kibet J.K., Ngari S.M.
2024-07-16 citations by CoLab: 14 Abstract
AbstractDye‐sensitized solar cells (DSSCs) are among the most attractive third‐generation photovoltaic technologies due to their low toxicity, versatility, roll‐to‐roll compatibility, ultralightness, and attractive power conversion efficiencies (PCEs). However, their transition from the laboratory scale to the industrial scale has been slow due to their inability to compete with silicon‐based cells in terms of efficiencies and stabilities. Research activities on DSSCs have been ongoing for several decades to improve the efficiency and cost‐effectiveness of photovoltaics but these attempts are still inadequate. Their chemical and physical properties must be refined to increase efficiency and commercialization. This review provides a concise overview of the recent advances taking place in the DSSCs research field, including molecular engineering technologies, the quest for superior carrier transport materials (CTMs), efficient sensitizers, and better electrodes. Also, this review compiles knowledge of the historical development of DSSCs, the current advancements such as control of surface morphologies, doping strategies, modeling and simulation, characterization, and recent cutting‐edge research happenings in photovoltaic research. Finally, nanostructured materials that have been used as photoelectrodes and the practical applications of DSSCs in internet of things (IoT) and portable electronics are examined to identify challenges and future advancements. The main aim of this work is to be a pathfinder for scientific researchers in this field exploring various energy harvesting materials and optimization strategies of different components of DSSCs.
Golonko P., Kochanowicz M., Miluski P., Kuwik M., Pisarska J., Pisarski W., Dorosz J., Leśniak M., Dorosz D., Basa A., Żmojda J.
2024-04-01 citations by CoLab: 1 Abstract
In this paper, we report on fabricating optical fibers with a controlled process of crystallization core during the drawing process. The research and synthesis of the core material of silica-germanium-antimony oxide glass were discussed. We also investigated the optical and luminescence properties were in relation to concentrating Eu2O3 and P2O5. Based on this investigation, we selected the most promising material for optical fiber core. In the next step, we drew optical fibers using a well-known rod-in-tube method. After drawing, we examine the optical fibers for luminescence shape changes. We observed a promising similarity between optical fibers and heat-treated samples with confirmed nanocrystals. Finally, XRD and TEM measurements confirm EuPO4 nanocrystals at the core of the optical fiber. Highlighting the successful control of crystallization in the one-step method used to draw optical fibers.
Asghar U., Asjad M.I., Riaz M.B., Muhammad T.
2024-03-06 citations by CoLab: 1 Abstract
In this article, the propagation of waves in micro-crystalline materials is governed by the structure of the strain wave equation and takes into consideration various dimensions of micro-crystalline. Micro-crystalline materials that are deserving of special attention in material physics. The strain wave equation represents the dynamic behavior associated with multiple phenomena of a physical nature. The new extended direct algebraic methodology is applied to acquire the different types of exact solitonic solutions. This technique stands out as one of the most effective approaches for producing a diverse set of exact solutions to nonlinear partial differential equations. By applying a new extended direct algebraic approach, we get solutions in the form of smooth periodic, anti-dark, anti-bell-shape, periodic bright, Combined bright-dark soliton, mixed-periodic solution, anti-kink formations, Stumpons, mixed periodic solitons, and decaying cusped solitons. Furthermore, two-dimensional, three-dimensional, and contour plots are created for different solutions, helping us make sense of their physical significance more clearly. The importance of the obtained results lies in their ability to represent diverse and complex phenomena in mathematical and physical systems.
Lebedeva Y.S., Smayev M.P., Budagovsky I.A., Fedyanina M.E., Sinev I.S., Kunkel T.S., Romashkin A.V., Smirnov P.A., Sherchenkov A.A., Kozyukhin S.A., Lazarenko P.I.
2023-12-01 citations by CoLab: 0 Abstract
The photoinduced crystallization of thin amorphous films based on the binary compound Sb2Se3 and the ternary compound Ge2Sb2Te5 under continuous-wave laser irradiation is studied. The optical parameters of amorphous and crystalline films are analyzed by optical and atomic force microscopies, ellipsometry, spectrophotometry, and Raman spectroscopy. The crystallization temperatures, optical band gaps, Urbach-tail lengths, the activation energies of electrical conductivity, as well as the spectral dependences of the refractive indices and the extinction coefficients, are determined. The crystallized regions of Sb2Se3 are characterized by the more pronounced inhomogeneity of reflectivity (grain size) compared to crystalline regions of Ge2Sb2Te5 produced with the same laser-beam parameters. An analysis of the topography of crystallized films shows qualitative differences in the crystallite sizes. The distinctions may be related to differences in the mechanism of photoinduced crystallization. The Sb2Se3 compound has a higher optical band gap in comparison with Ge2Sb2Te5 and lower absorbance in the visible and near-infrared region, which can reduce the optical losses in the elements of silicon integrated optics based on the phase-change materials, as well as extend the range of possible application of phase-change materials for optical elements and nanophotonics devices.
Ruan J., Zhong: T., Guo Y.
2023-11-01 citations by CoLab: 15 Abstract
The key elements that influence the properties and capabilities of particulate photocatalysts are their crystallinity, size, and surface active sites. However, simultaneously controlling these three variables remains a challenge. In this study, we present the first exploration into the use of a simple ethylenediaminetetraacetate (EDTA) etching technique to decrease the particle size and increase the surface active sites of photocatalysts while preserving their high crystallinity. By employing SrTiO3 as a model photocatalyst, we were able to create an ordered step nanostructure on the surface of sintered SrTiO3. As a result of the EDTA treatment, the particle size was reduced while the crystallinity was maintained. The separation of photogenerated electrons and holes is enhanced by the combination of reduced particle size and high crystallinity. To enhance chemical reaction activities, the organized surface nano-step structures serve as high-activity sites. As a result, when subjected to simulated light irradiation, the EDTA-treated SrTiO3 samples demonstrate improved photocatalytic performance for water splitting into H2 and O2 in a stoichiometric amount that is 3.8 times greater than that of untreated SrTiO3. Since EDTA interacts with most metals, this simple EDTA etching technique has the potential to be further developed to modify additional photocatalysts with exceptional performance for a variety of applications.
Semenov A.R., Litvinov V.G., Kholomina T.A., Ermachikhin A.V., Rybin N.B.
2023-10-18 citations by CoLab: 1 Abstract
The results of an experimental study of the surface morphology of zinc-oxide films and the electrical properties of structures based on a single-crystal Si/microcrystalline ZnO heterojunction are presented. An analysis of the structure of the zinc-oxide films grown in argon and oxygen atmospheres is carried out, and the size distribution of nanofibers grown on its surface is obtained. The capacitance–voltage characteristics of In/ZnO/n-Si/Al and Au/ZnO/n-Si/Al heterostructures are simulated. On the basis of calculations and comparison of the experimental and simulated dependences, the concentration of free charge carriers in the sample and the position of the Fermi level are determined, the presence of a fixed charge in the system is revealed, and the density of surface states is found based on the ratio of the voltage applied to the system and the surface potential at the interface between layers. The value of the built-in surface charge is calculated. The relationship between the material of the upper contacts and the capacitance–voltage and current–voltage characteristics of the system is studied. The resistance of the formed zinc-oxide films is calculated. The prevailing charge-transfer mechanisms are discussed. An empirical dependence of the surface potential of silicon on the voltage applied to the structure is revealed. The effect of technological modes for obtaining zinc-oxide films synthesized by spray pyrolysis on the surface structure, effective capacitance of the structure, density of electronic states, and processes of charge-carrier transfer in samples under the action of an electric field is analyzed.
Dimakopoulou F., Efthymiou C., Kourtellaris A., O'Malley C., Alaa Eldin Refat L., Tasiopoulos A., McArdle P., Papatriantafyllopoulou C.
CrystEngComm Q2 Q1
2023-10-04 citations by CoLab: 0 Abstract
The isolation of mixed-ligand compounds has attracted a considerable research interest as the synergy between the ligands results to species with interesting technological, environmental and biomedical applications. In this study,...
Semenov A.R., Litvinov V.G., Kholomina T.A., Ermachikhin A.V., Rybin N.B.
The results of an experimental study of the surface morphology of zinc oxide films and the electrical properties of structures based on the monocrystalline Si/microcrystalline ZnO heterojunction are presented. The structure of zinc oxide films grown in an atmosphere of argon and oxygen is analyzed, and the size distribution of nanoscale fibers grown on its surface is obtained. The capacitance-voltage characteristics of the In/ZnO/n-Si/Al and Au/ ZnO/n-Si/Al heterostructures have been simulated. Based on the calculations and comparison of experimental and model dependences, the concentration of free charge carriers in the sample and the position of the Fermi level were determined, the presence of a fixed charge in the structure was revealed, the density of surface states was found based on the ratio of the voltage applied to the structure and the surface potential at the interface of the materials of the layers of structures. The value of the built-in surface charge is calculated. The interrelation of the upper contact material with the volt-farad and volt-ampere characteristics of the structure is investigated. The resistance of the formed zinc oxide films is calculated. The prevailing charge transfer mechanisms are discussed. The influence of technological modes of obtaining zinc oxide films obtained by spray pyrolysis on the structure of the surface, the effective capacity of the structure, the density of electronic states, the processes of charge carrier transfer in samples under the action of an electric field is analyzed.
Semchenko A.V., Ayvazyan G.Y., Malyutina-Bronskaya V.V., Khakhomov S.A., Kovalenko D.L., Boiko A.A., Sidski V.V., Nestsiaronak A.V., Mayevsky A.A., Danilchenko K.D., Zhigulin D.V., Pilipenko V.A., Subasri R., Gaponenko N.V.
Photonics Q2 Q2 Open Access
2023-07-21 citations by CoLab: 7 PDF Abstract
In this work, we have investigated the photocurrent and spectral sensitivity of the silicon/SrTiO3:xNb/perovskite structures. The sol–gel method carried out the deposition of undoped SrTiO3 layers as well as niobium-doped (SrTiO3:Nb) layers at atomic concentrations of 3 and 6% Nb. The perovskite layer, CH3NH3PbI3−xClx, has been deposited by the vacuum co-evaporation technique. The layers have been characterized by scanning electron microscopy and X-ray diffraction measurements. The volt–ampere characteristics and spectral sensitivity of the fabricated samples have been measured under illumination with selective wavelengths of 405, 450, 520, 660, 780, 808, 905, 980, and 1064 nm of laser diodes. We have shown that for different configurations of applied voltage between silicon, SrTiO3:xNb, and CH3NH3PbI3−xClx, the structures are photosensitive ones with a variation of photocurrent from microamperes to milliamperes depending on Nb concentration in SrTiO3, and the highest photocurrent and spectral sensitivity values are observed when a SrTiO3:Nb layer with 3 at.% of Nb is used. A possible application of the proposed structure with a SrTiO3:Nb layer for perovskite solar cells and photodetectors is being discussed.
Huang H., Shi Q., Deng Y., Lei X., Zhang Q., Chen J., Deng X.
Nanomaterials Q1 Q2 Open Access
2023-06-30 citations by CoLab: 2 PDF Abstract
In order to improve laser transmission efficiency at 1053 nm and 527 nm, a potassium deuterium phosphate (DKDP) crystal (a key component of high-power laser systems) needs a bi-layer antireflection coating system on its incident surface. UV-curable polysiloxane coatings with a refractive index varying from 1.500 to 1.485 were prepared through the polycondensation of a methacryloxy propyl trimethoxylsilane (MPS) monomer with a controllable degree of hydrolysis. Additionally, the influence rule of the coating structure on the refractive index was intensively studied, and the primary factors that dominate the hydrolysis process were discussed. Further refractive index adjustment was achieved using only a small amount of dopant based on the polysiloxane coating with refractive index of 1.485, allowing for high antireflection of the bi-layer coating system at desired wavelengths to be achieved. In addition, high laser damage resistance and remarkable mechanical properties of the coating were simultaneously realized through the incorporation of a minor quantity of dopants, which benefited from the successful modulation of the intrinsic refractive index of the polysiloxane coating.
Chirkin M.V., Ustinov S.V., Mishin V.Y., Serebryakov A.E.
2023-06-16 citations by CoLab: 1 Abstract
A method is developed for determining threshold for the development of the instability of a gas discharge in a helium–neon ring laser, taking into account the distributed capacitance “positive column– grounded screen”. In the developed approach to the analysis of stability, the positive discharge of the column is replaced by an equivalent circuit, containing the series connection of negative dynamic resistance ρ and parallel RL circuits. An equivalent circuit can be designed by experimental studies of the linear response of a gas-discharge plasma to weak harmonic perturbations, presented in the form of frequency dependences of the complex resistance Z of the positive column. The calculation of the threshold of instability development in the electrical circuit of a bilateral discharge only on the basis of the experimentally recorded frequency dependence of the complex resistance of the positive column does not allow one to extend the quantitative analysis to conditions beyond the range of those in which the measurements are performed. To overcome this limitation, which hinders the search for the operating current, in which the development of instability is excluded for the entire temperature range of operation of helium–neon ring lasers, a model is developed that describes the positive column of the gas discharge. The boundary of the unstable state of the bilateral gas discharge in the space of parameters is found to be as follows: the resistance of ballast resistors, temperature, and circuit capacitance. The results obtained make it possible to maintain a bilateral DC discharge in a given range of temperature variation.
Zheng L., Wu X., Xue J., Zhu X.
2023-03-01 citations by CoLab: 1 Abstract
Abstract Improvement of endurance characteristics has been a hot area of phase-change memoryresearch. The properties of a phase-change material are believed to play an important role in device endurance. Repeated SET–RESET operation always leads to material failure problems, such as composition deviation and phase separation. Moreover, the quality of the electrode and the electrode contact also determine the endurance characteristics. In this study, C nanolayers were periodically inserted into the phase-change material Ge2Sb2Te5 (GST) to fabricate a superlattice-like (SLL) structure. Although some of C bonded with some of the Ge, Sb and Te atoms, more C atoms prefer nanometer-scale clusters at the grain boundary in the SLL film. The typical local configuration of GST was unchanged when artificial C nanolayers were inserted. Transmission electron microscopy experiments revealed that the bonded C atoms and nanometer-scale C clusters may occupy the spontaneously created holes and defects, preventing composition deviation of the phase-change material and prolonging the electrode service life. The contact surface between the phase-change material and the electrode is also improved. As a result, we found that the endurance cycle could be improved by up to 106 for a GST/C SLL film-based device.
Zheng L., Song Z., Song W., Zhu X., Song S.
2023-02-27 citations by CoLab: 7 Abstract
The similarity of bond lengths between doped element X and Te in the X–Te polyhedrons was important for the manipulation of GST properties. Nb-doped GST enhanced structural stability and resulted in a continuum of multi-level resistance states.
Vorobyov Y., Ermachikhin A., Yakubov A., Trusov E., Fedyanina M., Lazarenko P., Kozyukhin S.
2021-05-25 citations by CoLab: 6 Abstract
Abstract The non-Arrhenius behaviour of Ge2Sb2Te5 conductivity is attributed to the non-linear temperature dependence of the Fermi level, assuming extended state conduction by free holes. The temperature-dependent Fermi level is shown to alter values of activation energy and prefactor for conductivity so that their exact determination becomes impossible using the conductivity data alone. However, if one assumes the temperature dependence of the Fermi level to be a parabolic function. Then, two of three model parameters can be retrieved; to obtain the third parameter one has to make an assumption about the value of prefactor for conductivity. Applying the proposed analysis scheme to Ge2Sb2Te5, reasonable values of Fermi level position are obtained and the change of Fermi level as a result of resistance drift phenomenon is demonstrated.
Zhang W., Ma E.
2020-12-01 citations by CoLab: 120 Abstract
The global demand for data storage and processing is increasing exponentially. To deal with this challenge, massive efforts have been devoted to the development of advanced memory and computing technologies. Chalcogenide phase-change materials (PCMs) are currently at the forefront of this endeavor. In this Review, we focus on the mechanisms of the spontaneous structural relaxation – aging – of amorphous PCMs, which causes the well-known resistance drift issue that significantly reduces the device accuracy needed for phase-change memory and computing applications. We review the recent breakthroughs in uncovering the structural origin, achieved through state-of-the-art experiments and ab initio atomistic simulations. Emphasis will be placed on the evolving atomic-level details during the relaxation of the complex amorphous structure. We also highlight emerging strategies to control aging, inspired by the in-depth structural understanding, from both materials science and device engineering standpoints, that offer effective solutions to reduce the resistance drift. In addition, we discuss an important new paradigm – machine learning – and the potential power it brings in interrogating amorphous PCMs as well as other disordered alloy systems. Finally, we present an outlook to comment on future research opportunities in amorphous PCMs, as well as on their reduced aging tendency in other advanced applications such as non-volatile photonics.
Ermachikhin A.V., Vorobyov Y.V., Maslov A.D., Trusov E.P., Litvinov V.G.
2020-10-09 citations by CoLab: 3 Abstract
It is shown that the use of both sides of solar cells created with the heterojunction technology makes possible an increase in the solar-cell efficiency. The difference in illumination of the front and back sides is associated with transformation of the blue part of the spectrum, which is shown by the example of the spectral dispersion of the quantum efficiency. The average difference between the quantum efficiency for both sides is ~11%. The short-circuit current density with the power of the solar spectrum at sea level from 400 to 1100 nm is 36.3 mA/cm2 for the front side and 32.7 mA/cm2 for the back side. The decrease amounts to 9.7%.
Lee J., Wey M.
2020-08-01 citations by CoLab: 9 Abstract
In this study, poly(vinyl alcohol)/platinum/nitrogen-doped titanium dioxide/strontium titanate composite (PVA/Pt/NT/STO) porous films with adjustable pore sizes were successfully synthesized using the facile etching SiO2 method. This enhanced the light transmittance and contact rate between the photocatalyst and solution. The effects of the size and number of the pores on the hydrogen production rate were studied under simulated sunlight. The pore size of the PVA/Pt/NT/STO film increased with increasing particle size of the as-prepared SiO2, and the photocatalytic hydrogen production efficiency increased with increasing pore size and number. Due to the formation of pores on the film, the light transmittance and charge separation of the film increased. Owing to the good light transmittance and charge separation of the porous PVA/Pt/NT/STO film, the optimal photocatalytic hydrogen production rate of the PVA/Pt/NT/STO-8S-I-20 reached 34,895 μmol/h/g when the alcohol solvent, synthesis time, and SiO2 concentration were isopropanol, 20 h, and 8 wt%, respectively. Furthermore, the photocatalytic hydrogen production rate was approximately three times higher than that of the dense PVA/Pt/NT/STO film.
Funck C., Bäumer C., Wiefels S., Hennen T., Waser R., Hoffmann-Eifert S., Dittmann R., Menzel S.
2020-07-21 citations by CoLab: 22 Abstract
The presented study considers the electronic conduction across a $\mathrm{SrTi}{\mathrm{O}}_{3}\text{/}\mathrm{Pt}$ Schottky electrode in a resistive switching cell. It is generally accepted that the resistive switching effect is based on the migration of oxygen vacancies, which can be understood as mobile donors. In the experimental approach, a $\mathrm{Nb}:\mathrm{SrTi}{\mathrm{O}}_{3}\text{/}\mathrm{SrTi}{\mathrm{O}}_{3}\text{/}\mathrm{Pt}$ resistive switching cell is fabricated and tested for its electronic and resistive switching characteristics. Using different voltage stimuli, several analog resistance states are realized. Afterwards, the electrical transport properties under different applied voltages and temperatures are measured for each analog resistive state. To gain physical insight into the analog resistive switching a numerical simulation model is developed. The electronic conduction is calculated based on the single band transport theory and a phonon scattering theory accounting for polar material systems. The simulation model allows testing of the conduction in these resistive switching cells by using different doping (oxygen vacancy) concentrations. Combining the simulation model and the experiment, it delivers a comprehensive physical description for the conduction. By means of simulation, the energy resolved current transport across the Schottky barrier is analyzed. It forms a peaklike distribution, originating from the limited thermal excitation and tunneling probability across the $\mathrm{SrTi}{\mathrm{O}}_{3}\text{/}\mathrm{Pt}$ Schottky barrier. Thus, the conduction processes in all states are identified as a balance between a thermally assisted tunneling effect and a phonon dominated bulk transport. Applying this understanding, the resistive switching effect is reduced to a modification of the Schottky tunnel barrier, based on the rearrangement of oxygen vacancies. Thus a low vacancy concentration leads to a high and wide tunneling barrier, which is reduced and shortened for higher concentrations. All resistance states in between are understood as an adjustment of intermediate tunneling barriers. The physical insights leading to the realization of analog resistance states is mandatory to realize new types of neuromorphic computing circuits based on resistive switching devices. Furthermore, the obtained results could be easily transferred to other systems where a static doping concentration applies. This makes the results highly interesting to other applications in the field of electronic oxides and Schottky barrier dominated systems.
Vorobyov Y.V., Yakubov A.O., Ermachikhin A.V.
Abstract Results of studies of conductivity activation energy and its evolution during the aging process are presented for the common phase change material Ge2Sb2Te5. The evolution of temperature dependence of conductivity during quasi-isothermal annealing are interpreted in the framework of simple Arrhenius model as the change of two corresponding parameters: activation energy and pre-exponential factor. It is shown, that the change in resistivity of the Ge2Sb2Te5 during aging is attributed to the simultaneous change of both parameters of the Arrhenius equation, that is, activation energy and pre-exponential factor. Temperature dependencies of those parameters are shown as well, and the Meyer-Neldel rule for conductivity of Ge2Sb2Te5 is tested on the basis of the obtained data.
Khan R.S., Dirisaglik F., Gokirmak A., Silva H.
2020-06-22 citations by CoLab: 10 Abstract
Resistance drift in amorphous Ge2Sb2Te5 is experimentally characterized in melt-quenched line cells in the range of 300 K to 125 K and is observed to follow the previously reported power-law behavior with drift coefficients in the range of 0.07 to 0.11 in the dark, linearly decreasing with 1/kT. While these drift coefficients measured in the dark are similar to commonly observed drift coefficients (∼0.1) at and above room temperature, measurements under light show a significantly lower drift coefficient (0.05 under illumination vs 0.09 in the dark at 150 K). Periodic on/off switching of light shows a sudden decrease/increase in resistance, attributed to photo-excited carriers, followed by a very slow response (∼30 min at 150 K) attributed to contribution of electron traps and slow trap-to-trap charge exchanges. A device-level electronic model is used to relate these experimental findings to gradual charging of electron traps in amorphous Ge2Sb2Te5, which gives rise to growth of a potential barrier for holes in time and, hence, resistance drift.
Ujiie K., Kojima T., Ota K., Phuenhinlad P., Pleuksachat S., Meethong N., Itoi T., Uekawa N.
2020-04-01 citations by CoLab: 7 Abstract
Uniform, micron-sized SrTiO3 particles do not tend to aggregate, and the low surface area of larger particles can be improved by incorporating porous structures, thus offering superior performance for a range of applications. In this study, submicron-to micron-sized SrTiO3 particles were prepared using hot water or hydrothermal conversion of spherical hydrous titania (TiO2·nH2O) and porous hydrous titania. When spherical hydrous titania particles were employed as the starting material, spherical SrTiO3 particles of hydrous titania were obtained via treatment at 120 °C for 24 h. Similarly, the use of porous hydrous titania particles treated at 90 °C for 48 h resulted in spherical porous SrTiO3 particles with macropores of porous hydrous titania. These porous SrTiO3 particles have a specific surface area of ~115 m2/g, which is one of the largest among micron-sized SrTiO3 particles, thereby making them suitable for use as catalysts or photocatalysts.
Xu M., Qiao C., Xue K., Tong H., Cheng X., Wang S., Wang C., Ho K., Xu M., Miao X.
2020-04-01 citations by CoLab: 18 Abstract
A novel phase-change material K2Sb8Se13 with two amorphous phases was thoroughly investigated for multi-state data storage.
Le Gallo M., Sebastian A.
2020-03-30 citations by CoLab: 278 Abstract
Phase-change memory (PCM) is an emerging non-volatile memory technology that has recently been commercialized as storage-class memory in a computer system. PCM is also being explored for non-von Neumann computing such as in-memory computing and neuromorphic computing. Although the device physics related to the operation of PCM have been widely studied since its discovery in the 1960s, there are still several open questions relating to their electrical, thermal, and structural dynamics. In this article, we provide an overview of the current understanding of the main PCM device physics that underlie the read and write operations. We present both experimental characterization of the various properties investigated in nanoscale PCM devices as well as physics-based modeling efforts. Finally, we provide an outlook on some remaining open questions and possible future research directions.
Elliott S.R.
2020-03-23 citations by CoLab: 25 Abstract
'Phase-change' memory materials, such as the canonical composition Ge2Sb2Te5, are being actively researched for non-volatile resistive random-access memory applications. In these devices, ultra-rapid reversible transformations between metastable highly electrically conducting (degenerate-semiconducting) crystalline and more electrically resistive (semiconducting) glassy phases are produced by the application of appropriate voltage pulses. Multilevel programming, wherein more than two metastable resistance states can be stored in the memory material as different proportions of partially glassy/crystalline regions, allows more than one bit to be stored per memory cell. However, this route to increasing data density, without recourse to device-size down-scaling, is threatened by the phenomenon of 'resistance drift', wherein the electrical resistance of the glassy phase slowly increases with time, following a weak power-law dependence, after being written with a voltage pulse. In this paper, we propose an intrinsic electronic mechanism for the resistance drift, particularly valid at ambient temperature and below, by identifying it with the phenomenon of persistent photoconductivity that is commonly observed in a wide range of disordered semiconductors. We develop a model for it in terms of the long-time, deep-trap release and subsequent recombination of charge carriers, akin to that which is believed to be responsible for the long-time photocurrent decay in amorphous semiconductors, such as hydrogenated amorphous silicon. In this case, the parameters controlling the resistance drift are the widths of the (localized) valence- and conduction-band tails in the vicinity of the bandgap. Hence, there is the potential for mitigating resistance drift in the amorphous state of phase-change memory materials by suitable material engineering (e.g. via compositional or fabricational control) to control the extent of band-tailing, thereby facilitating the future introduction of multistate memory.
Ma C., Luo Z., Huang W., Zhao L., Chen Q., Lin Y., Liu X., Chen Z., Liu C., Sun H., Jin X., Yin Y., Li X.
2020-03-18 citations by CoLab: 213 PDF Abstract
Next-generation non-volatile memories with ultrafast speed, low power consumption, and high density are highly desired in the era of big data. Here, we report a high performance memristor based on a Ag/BaTiO3/Nb:SrTiO3 ferroelectric tunnel junction (FTJ) with the fastest operation speed (600 ps) and the highest number of states (32 states or 5 bits) per cell among the reported FTJs. The sub-nanosecond resistive switching maintains up to 358 K, and the write current density is as low as 4 × 103 A cm−2. The functionality of spike-timing-dependent plasticity served as a solid synaptic device is also obtained with ultrafast operation. Furthermore, it is demonstrated that a Nb:SrTiO3 electrode with a higher carrier concentration and a metal electrode with lower work function tend to improve the operation speed. These results may throw light on the way for overcoming the storage performance gap between different levels of the memory hierarchy and developing ultrafast neuromorphic computing systems. Memristor devices based on ferroelectric tunnel junctions are promising, but suffer from quite slow switching times. Here, the authors report on ultrafast switching times at and above room temperature of 600ps in Ag/BaTiO3/Nb:SrTiO3 based ferroelectric tunnel junctions.
Li S., Li M., Tao A., Song M., Wang B., Niu J., Yu F., Wu Y.
2020-03-13 citations by CoLab: 6 Abstract
A series of hierarchically porous SrTiO3 films with different pore structure characteristics from bicontinuous macroporous–mesoporous structure to ordered and fragmented structures have been synthesized using sol–gel method, by controlling the competition between polyethylene glycol (PEG)-induced phase separation and sol–gel transition. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis, X-ray diffractometry (XRD) and photoluminescence (PL) spectroscopy were used to characterize the as-prepared samples. The bicontinuous structured SrTiO3 porous film constructed by irregular grains possessed three-dimensional (3D) interconnected network with both macropores (80–400 nm) and mesopores (1–10 nm), which provides abundant active sites (the specific surface area up to 121.9 m2/g) and ensures fast mass transfer simultaneously. In addition, PL spectra illustrated that the film consisting of 3D bicontinuous macroporous– and mesopores has a relatively low photocarrier recombination rate. As a result, the SrTiO3 film with 3D bicontinuous porous structure exhibits more outstanding photocatalytic behavior with high degradation capability for Rhodamine B (RhB) (99.8% after 90 min irradiation by 500 W mercury lamp) than the others. Moreover, nearly 80% of the degradation efficiency can be achieved after five cycles.
Khokhar M.Q., Hussain S.Q., Kim S., Lee S., Pham D.P., Kim Y., Cho E., Yi J.
2020-02-01 citations by CoLab: 17 Abstract
This inclusive study provides detailed information regarding the evolution of rear emitter silicon heterojunction solar cells. Silicon heterojunction (SHJ) solar cells of a p-type on the rear side have garnered increasing attention for various reasons. First, owing to a limitation of the p-type hydrogenated amorphous silicon layer, further optimization relative to an n-type cannot be achieved, and an accumulation of electrons at the front side allows utilizing an n-type wafer to affirm a lateral current transport. Second, better thin n-type nanocrystalline silicon (oxide) contact layers compared to p-type wafers are grown, and allow greater freedom in the structural design. The optical properties of the front side’s transparent conductive oxide (TCO) layer can be emphasized owing to a lateral transport on the cells, and majority of the carriers are affirmed through a Si substrate. In the instance of a rear emitter, the TCO layer is in relief to an adjustment inhibiting the contact resistance between TCO/a-Si:H(p). The fabrication was done in such a manner of SHJ rear emitter solar cells that they achieve greater optimization and overall efficiency of 23.46%.
Xie J., Lei K., Wang H., Wang C., Liu B., Zhang L., Bai P.
2020-01-13 citations by CoLab: 10 Abstract
The microstructure of the catalyst material is one of the most important factors affecting the photocatalytic performance. In this study, inverse opal structure strontium titanate (SrTiO3, STO) materials with different pore sizes (from 75 to 123 nm) were prepared, and employed as photocatalysts in the degradation of rhodamine B (RhB) dye. The results suggest that the highest photodegradation rate of the inverse opal structure photocatalyst reaches to 88.03%, which is greater than that of the non-inverse opal structure (50.42%) due to its complex three-dimensional porous microstructure. The effect of the pore size of the inverse opal structure STO on the photocatalytic properties was investigated. As the pore size of the inverse opal microstructure decreases, the photocatalytic degradation rate increases regularly, attributing to effective capture of light with decreasing of pore size. The photocatalytic degradation mechanism of inverse opal structure with different pore sizes is discussed in this work.
Total publications
46
Total citations
80
Citations per publication
1.74
Average publications per year
4.18
Average coauthors
4.07
Publications years
2013-2023 (11 years)
h-index
5
i10-index
0
m-index
0.45
o-index
6
g-index
6
w-index
0
Metrics description

Top-100

Fields of science

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Condensed Matter Physics, 9, 19.57%
Electronic, Optical and Magnetic Materials, 7, 15.22%
General Materials Science, 5, 10.87%
Physics and Astronomy (miscellaneous), 5, 10.87%
General Physics and Astronomy, 4, 8.7%
Atomic and Molecular Physics, and Optics, 4, 8.7%
Instrumentation, 4, 8.7%
Surfaces, Coatings and Films, 2, 4.35%
Mechanical Engineering, 2, 4.35%
General Engineering, 2, 4.35%
Mechanics of Materials, 2, 4.35%
General Medicine, 1, 2.17%
Electrical and Electronic Engineering, 1, 2.17%
General Energy, 1, 2.17%
Applied Mathematics, 1, 2.17%
Acoustics and Ultrasonics, 1, 2.17%
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9

Journals

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Citing journals

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Journal not defined, 21, 26.25%
Show all (6 more)
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Publishers

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Organizations from articles

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Organization not defined, 18, 29.03%
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Countries from articles

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Russia, 42, 85.71%
Country not defined, 4, 8.16%
Belarus, 2, 4.08%
Germany, 1, 2.04%
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Citing organizations

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Organization not defined, 20, 19.05%
Show all (13 more)
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Citing countries

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Russia, 40, 49.38%
China, 7, 8.64%
Belarus, 5, 6.17%
Country not defined, 4, 4.94%
France, 3, 3.7%
USA, 2, 2.47%
Ireland, 2, 2.47%
Poland, 2, 2.47%
Germany, 1, 1.23%
Ukraine, 1, 1.23%
Portugal, 1, 1.23%
Armenia, 1, 1.23%
India, 1, 1.23%
Iran, 1, 1.23%
Canada, 1, 1.23%
Kenya, 1, 1.23%
Cyprus, 1, 1.23%
Lebanon, 1, 1.23%
Mexico, 1, 1.23%
Moldova, 1, 1.23%
Pakistan, 1, 1.23%
Saudi Arabia, 1, 1.23%
Czech Republic, 1, 1.23%
Sweden, 1, 1.23%
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  • We do not take into account publications without a DOI.
  • Statistics recalculated daily.
Александр Антонович Корнилович, Владимир Георгиевич Литвинов, Александр Валерьевич Ермачихин, Дмитрий Сергеевич Кусакин
RU2538073C2, 2014
Александр Антонович Корнилович, Владимир Георгиевич Литвинов, Александр Валерьевич Ермачихин, Дмитрий Сергеевич Кусакин
RU2534382C1, 2014
Company/Organization
Position
Researcher
Employment type
Part time
Years
2023 — present
Position
Senior researcher
Employment type
Part time
Years
2015 — present
Position
Associate professor
Employment type
Part time
Years
2015 — present