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Papers by Alexander A Lebedev

Наносистемы: физика, химия, математика, Feb 24, 2016

Materials Science Forum

Hysteresis response of epitaxially grown graphene nanoribbons devices on semi-insulating 4H-SiC i... more Hysteresis response of epitaxially grown graphene nanoribbons devices on semi-insulating 4H-SiC in the armchair and zigzag directions is evaluated and studied. The influence of the orientation of fabrication and dimensions of graphene nanoribbons on the hysteresis effect reveals the metallic and semiconducting nature graphene nanoribbons. The hysteresis response of armchair based graphene nanoribbon side gate and top gated devices implies the influence of gate field electric strength and the contribution of surface traps, adsorbents, and initial defects on graphene as the primary sources of hysteresis. Additionally, passivation with AlOx and top gate modulation decreased the hysteresis and improved the current-voltage characteristics.

Russian Military Medical Academy Reports

Cognitive disorders are currently being considered within the framework of the most pressing prob... more Cognitive disorders are currently being considered within the framework of the most pressing problems of modern clinical neurology in particular and medicine in general. Their significance is due to both the significant negative impact on the health and quality of life of patients, as well as the condition of their immediate relatives and society as a whole. In addition, widespread violations of higher cortical functions significantly affect the financial and economic indicators of individual groups of individuals and the state. These provisions determine the need to search for new highly effective ways of managing patients. The solution of this problem is impossible without the introduction of effective diagnostic methods that allow rapid and qualitative verification of the pathological process, especially at its early stages. Given the fact that Alzheimers disease plays a major role in the development of dementia in old age, the development of its diagnostic methods is the interes...

Semiconductors

The effect of proton irradiation (proton energy 15 MeV) on the parameters of high-voltage 4H-SiC ... more The effect of proton irradiation (proton energy 15 MeV) on the parameters of high-voltage 4H-SiC integrated Schottky diodes (JBS) was studied for the first time in the operating temperature range Ti (23 and 175oC). The blocking voltage of the diodes under study, Ub, was 600 and 1700 V. For devices with U_b = 600 V, the fluence range was 5·1013-1·1014 cm-2; for devices with U_b=1700 V, the fluence range was 3·1013-6·1013 cm-2. An increase in the irradiation temperature leads to a noticeable decrease in the effect of irradiation on the current-voltage characteristics of the diodes. The effect of annealing on the current-voltage characteristics of irradiated devices is studied. Keywords: Silicon carbide, Schottky diodes, proton irradiation, current-voltage characteristics, annealing.

Procedia Engineering, 2015

Ultrasensitive gas sensor based on epitaxial graphene on SiC has been fabricated. The sensor exhi... more Ultrasensitive gas sensor based on epitaxial graphene on SiC has been fabricated. The sensor exhibits strong and reproducible response to nitrogen dioxide (NO2) in the concentration in air down to 1 part-per billion (ppb). Prototype of the transportable device for environmental monitoring allows fast and reproducible measurements of NO2 concentration in the range typical for environmental pollution (5 ppb-50 ppb).

Materials, 2021

The radiation hardness of silicon carbide with respect to electron and proton irradiation and its... more The radiation hardness of silicon carbide with respect to electron and proton irradiation and its dependence on the irradiation temperature are analyzed. It is shown that the main mechanism of SiC compensation is the formation of deep acceptor levels. With increasing the irradiation temperature, the probability of the formation of these centers decreases, and they are partly annealed out. As a result, the carrier removal rate in SiC becomes ~6 orders of magnitude lower in the case of irradiation at 500 °C. Once again, this proves that silicon carbide is promising as a material for high-temperature electronics devices.

Materials Science Forum, 2006

The investigated AlGaN epitaxial layers were grown by hydride vapor phase epitaxy (HVPE) on a com... more The investigated AlGaN epitaxial layers were grown by hydride vapor phase epitaxy (HVPE) on a commercial P+ SiC substrate or on an N+ SiC Lely substrate with a p+ SiC layer previously grown by sublimation epitaxy. To investigate the electrical characteristics of the n-p heterojunction, mesa structures of 100, 200 and 1500 microns in diameter were fabricated by reactive ion etching. Investigation of electrical characteristics shows good quality of grown n- AlGaN/p-SiC heterojunctions. This shows applicability of this technological combination for producing n-AlGaN/p-SiC bipolar or FET transistors.

Materials, 2021

This work is devoted to the development and optimization of the parameters of graphene-based sens... more This work is devoted to the development and optimization of the parameters of graphene-based sensors. The graphene films used in the present study were grown on semi-insulating 6H-SiC substrates by thermal decomposition of SiC at the temperature of ~1700 °C. The results of measurements by Auger and Raman spectroscopies confirmed the presence of single-layer graphene on the silicon carbide surface. Model approach to the theory of adsorption on epitaxial graphene is presented. It is demonstrated that the Green-function method in conjunction with the simple substrate models permit one to obtain analytical results for the charge transfer between adsorbed molecules and substrate. The sensor structure was formed on the graphene film by laser. Initially, a simpler gas sensor was made. The sensors developed in this study demonstrated sensitivity to the NO2 concentration at the level of 1–0.01 ppb. The results obtained in the course of development and the results of testing of the graphene-b...

Biosensors, 2021

In this study, we discuss the mechanisms behind changes in the conductivity, low-frequency noise,... more In this study, we discuss the mechanisms behind changes in the conductivity, low-frequency noise, and surface morphology of biosensor chips based on graphene films on SiC substrates during the main stages of the creation of biosensors for detecting influenza viruses. The formation of phenylamine groups and a change in graphene nano-arrangement during functionalization causes an increase in defectiveness and conductivity. Functionalization leads to the formation of large hexagonal honeycomb-like defects up to 500 nm, the concentration of which is affected by the number of bilayer or multilayer inclusions in graphene. The chips fabricated allowed us to detect the influenza viruses in a concentration range of 10−16 g/mL to 10−10 g/mL in PBS (phosphate buffered saline). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed that these defects are responsible for the inhomogeneous aggregation of antibodies and influenza viruses over the functionalized graphene surf...

Annalen der Physik, 2017

Graphene nanoribbons show unique properties and have attracted a lot of attention in the recent p... more Graphene nanoribbons show unique properties and have attracted a lot of attention in the recent past. Intensive theoretical and experimental studies on such nanostructures at both the fundamental and application-oriented levels have been performed. The present paper discusses the suitability of graphene nanoribbons devices for nanoelectronics and focuses on three specific device types-graphene nanoribbon MOSFETs, side-gate transistors, and three terminal junctions. It is shown that, on the one hand, experimental devices of each type of the three nanoribbon-based structures have been reported, that promising performance of these devices has been demonstrated and/or predicted, and that in part they possess functionalities not attainable with conventional semiconductor devices. On the other hand, it is emphasized that-in spite of the remarkable progress achieved during the past 10 yearsgraphene nanoribbon devices still face a lot of problems and that their prospects for future applications remain unclear.

AIP Conference Proceedings, 2007

In addition to possessing unique electrical properties, silicon carbide (SiC) can crystallize in ... more In addition to possessing unique electrical properties, silicon carbide (SiC) can crystallize in different modifications (polytypes). Having the same chemical nature, SiC polytypes may significantly differ in their electrical parameters. In recent years, the world's interest in fabrication and study of heteropolytype structures based on silicon carbide has considerably increased. This presentation considers studies concerned with fabrication technologies of various

Crystals, 2020

The modern development of the nuclear industry, nuclear energy, and aerospace technology is in di... more The modern development of the nuclear industry, nuclear energy, and aerospace technology is in dire need of the development of a new generation of electronics capable of operating at elevated levels of radiation and high temperatures and in chemically active environments [...]

Technical Physics, 2020

We investigate the possibility of integration of epitaxial SiC and AlN technologies using opposit... more We investigate the possibility of integration of epitaxial SiC and AlN technologies using opposite faces of the common SiC substrate (AlN epitaxy is performed at the final stage), preserving the initial quality of the preliminarily prepared SiC layers. In particular, we study the influence of AlN heteroepitaxy and accompanying elastic stresses on the redistribution of a doping impurity in SiC layers, as well as the transformation of the local values of the breakdown voltage of barrier diodes, which is associated with this process. As the diagnostic procedure in studying possible negative consequences of durable growth (about 3 h, 60 μm), we have measured reverse branches of the current-voltage characteristics of surface-barrier diode matrices of the Au-SiC type, which have intentionally been formed before and immediately after AlN epitaxy and then removed after the appropriate measuring procedure. Statistical processing of the breakdown voltages (including the calculation of histograms) shows that the variation of mean values and dispersion for the n-as well as players is insignificant.

Materials Science Forum, 1997

Semiconductors, 1999

An analysis of experimental data on the influence of native defects of the crystalline lattice on... more An analysis of experimental data on the influence of native defects of the crystalline lattice on polytypism in silicon carbide has been performed. A simple analytical expression, which links the degree of hexagonality of the polytype with the concentration of carbon and silicon vacancies, was obtained. The possible dependence of the model parameters on the experimental conditions is investigated.

Life Science Journal

Analysis of the national and foreign publications dedicated to the graphene production, its prope... more Analysis of the national and foreign publications dedicated to the graphene production, its properties study and graphene-based device prototyping. It is demonstrated that one of the most attractive devices for practical realization is a gas sensor based on the graphene film. Also it is demonstrated that a method of silicon carbide thermal decomposition is the advanced technology for the graphene electronics realization.

Materials Science Forum, 2004

ABSTRACT

Наносистемы: физика, химия, математика, Feb 24, 2016

Materials Science Forum

Hysteresis response of epitaxially grown graphene nanoribbons devices on semi-insulating 4H-SiC i... more Hysteresis response of epitaxially grown graphene nanoribbons devices on semi-insulating 4H-SiC in the armchair and zigzag directions is evaluated and studied. The influence of the orientation of fabrication and dimensions of graphene nanoribbons on the hysteresis effect reveals the metallic and semiconducting nature graphene nanoribbons. The hysteresis response of armchair based graphene nanoribbon side gate and top gated devices implies the influence of gate field electric strength and the contribution of surface traps, adsorbents, and initial defects on graphene as the primary sources of hysteresis. Additionally, passivation with AlOx and top gate modulation decreased the hysteresis and improved the current-voltage characteristics.

Russian Military Medical Academy Reports

Cognitive disorders are currently being considered within the framework of the most pressing prob... more Cognitive disorders are currently being considered within the framework of the most pressing problems of modern clinical neurology in particular and medicine in general. Their significance is due to both the significant negative impact on the health and quality of life of patients, as well as the condition of their immediate relatives and society as a whole. In addition, widespread violations of higher cortical functions significantly affect the financial and economic indicators of individual groups of individuals and the state. These provisions determine the need to search for new highly effective ways of managing patients. The solution of this problem is impossible without the introduction of effective diagnostic methods that allow rapid and qualitative verification of the pathological process, especially at its early stages. Given the fact that Alzheimers disease plays a major role in the development of dementia in old age, the development of its diagnostic methods is the interes...

Semiconductors

The effect of proton irradiation (proton energy 15 MeV) on the parameters of high-voltage 4H-SiC ... more The effect of proton irradiation (proton energy 15 MeV) on the parameters of high-voltage 4H-SiC integrated Schottky diodes (JBS) was studied for the first time in the operating temperature range Ti (23 and 175oC). The blocking voltage of the diodes under study, Ub, was 600 and 1700 V. For devices with U_b = 600 V, the fluence range was 5·1013-1·1014 cm-2; for devices with U_b=1700 V, the fluence range was 3·1013-6·1013 cm-2. An increase in the irradiation temperature leads to a noticeable decrease in the effect of irradiation on the current-voltage characteristics of the diodes. The effect of annealing on the current-voltage characteristics of irradiated devices is studied. Keywords: Silicon carbide, Schottky diodes, proton irradiation, current-voltage characteristics, annealing.

Procedia Engineering, 2015

Ultrasensitive gas sensor based on epitaxial graphene on SiC has been fabricated. The sensor exhi... more Ultrasensitive gas sensor based on epitaxial graphene on SiC has been fabricated. The sensor exhibits strong and reproducible response to nitrogen dioxide (NO2) in the concentration in air down to 1 part-per billion (ppb). Prototype of the transportable device for environmental monitoring allows fast and reproducible measurements of NO2 concentration in the range typical for environmental pollution (5 ppb-50 ppb).

Materials, 2021

The radiation hardness of silicon carbide with respect to electron and proton irradiation and its... more The radiation hardness of silicon carbide with respect to electron and proton irradiation and its dependence on the irradiation temperature are analyzed. It is shown that the main mechanism of SiC compensation is the formation of deep acceptor levels. With increasing the irradiation temperature, the probability of the formation of these centers decreases, and they are partly annealed out. As a result, the carrier removal rate in SiC becomes ~6 orders of magnitude lower in the case of irradiation at 500 °C. Once again, this proves that silicon carbide is promising as a material for high-temperature electronics devices.

Materials Science Forum, 2006

The investigated AlGaN epitaxial layers were grown by hydride vapor phase epitaxy (HVPE) on a com... more The investigated AlGaN epitaxial layers were grown by hydride vapor phase epitaxy (HVPE) on a commercial P+ SiC substrate or on an N+ SiC Lely substrate with a p+ SiC layer previously grown by sublimation epitaxy. To investigate the electrical characteristics of the n-p heterojunction, mesa structures of 100, 200 and 1500 microns in diameter were fabricated by reactive ion etching. Investigation of electrical characteristics shows good quality of grown n- AlGaN/p-SiC heterojunctions. This shows applicability of this technological combination for producing n-AlGaN/p-SiC bipolar or FET transistors.

Materials, 2021

This work is devoted to the development and optimization of the parameters of graphene-based sens... more This work is devoted to the development and optimization of the parameters of graphene-based sensors. The graphene films used in the present study were grown on semi-insulating 6H-SiC substrates by thermal decomposition of SiC at the temperature of ~1700 °C. The results of measurements by Auger and Raman spectroscopies confirmed the presence of single-layer graphene on the silicon carbide surface. Model approach to the theory of adsorption on epitaxial graphene is presented. It is demonstrated that the Green-function method in conjunction with the simple substrate models permit one to obtain analytical results for the charge transfer between adsorbed molecules and substrate. The sensor structure was formed on the graphene film by laser. Initially, a simpler gas sensor was made. The sensors developed in this study demonstrated sensitivity to the NO2 concentration at the level of 1–0.01 ppb. The results obtained in the course of development and the results of testing of the graphene-b...

Biosensors, 2021

In this study, we discuss the mechanisms behind changes in the conductivity, low-frequency noise,... more In this study, we discuss the mechanisms behind changes in the conductivity, low-frequency noise, and surface morphology of biosensor chips based on graphene films on SiC substrates during the main stages of the creation of biosensors for detecting influenza viruses. The formation of phenylamine groups and a change in graphene nano-arrangement during functionalization causes an increase in defectiveness and conductivity. Functionalization leads to the formation of large hexagonal honeycomb-like defects up to 500 nm, the concentration of which is affected by the number of bilayer or multilayer inclusions in graphene. The chips fabricated allowed us to detect the influenza viruses in a concentration range of 10−16 g/mL to 10−10 g/mL in PBS (phosphate buffered saline). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed that these defects are responsible for the inhomogeneous aggregation of antibodies and influenza viruses over the functionalized graphene surf...

Annalen der Physik, 2017

Graphene nanoribbons show unique properties and have attracted a lot of attention in the recent p... more Graphene nanoribbons show unique properties and have attracted a lot of attention in the recent past. Intensive theoretical and experimental studies on such nanostructures at both the fundamental and application-oriented levels have been performed. The present paper discusses the suitability of graphene nanoribbons devices for nanoelectronics and focuses on three specific device types-graphene nanoribbon MOSFETs, side-gate transistors, and three terminal junctions. It is shown that, on the one hand, experimental devices of each type of the three nanoribbon-based structures have been reported, that promising performance of these devices has been demonstrated and/or predicted, and that in part they possess functionalities not attainable with conventional semiconductor devices. On the other hand, it is emphasized that-in spite of the remarkable progress achieved during the past 10 yearsgraphene nanoribbon devices still face a lot of problems and that their prospects for future applications remain unclear.

AIP Conference Proceedings, 2007

In addition to possessing unique electrical properties, silicon carbide (SiC) can crystallize in ... more In addition to possessing unique electrical properties, silicon carbide (SiC) can crystallize in different modifications (polytypes). Having the same chemical nature, SiC polytypes may significantly differ in their electrical parameters. In recent years, the world's interest in fabrication and study of heteropolytype structures based on silicon carbide has considerably increased. This presentation considers studies concerned with fabrication technologies of various

Crystals, 2020

The modern development of the nuclear industry, nuclear energy, and aerospace technology is in di... more The modern development of the nuclear industry, nuclear energy, and aerospace technology is in dire need of the development of a new generation of electronics capable of operating at elevated levels of radiation and high temperatures and in chemically active environments [...]

Technical Physics, 2020

We investigate the possibility of integration of epitaxial SiC and AlN technologies using opposit... more We investigate the possibility of integration of epitaxial SiC and AlN technologies using opposite faces of the common SiC substrate (AlN epitaxy is performed at the final stage), preserving the initial quality of the preliminarily prepared SiC layers. In particular, we study the influence of AlN heteroepitaxy and accompanying elastic stresses on the redistribution of a doping impurity in SiC layers, as well as the transformation of the local values of the breakdown voltage of barrier diodes, which is associated with this process. As the diagnostic procedure in studying possible negative consequences of durable growth (about 3 h, 60 μm), we have measured reverse branches of the current-voltage characteristics of surface-barrier diode matrices of the Au-SiC type, which have intentionally been formed before and immediately after AlN epitaxy and then removed after the appropriate measuring procedure. Statistical processing of the breakdown voltages (including the calculation of histograms) shows that the variation of mean values and dispersion for the n-as well as players is insignificant.

Materials Science Forum, 1997

Semiconductors, 1999

An analysis of experimental data on the influence of native defects of the crystalline lattice on... more An analysis of experimental data on the influence of native defects of the crystalline lattice on polytypism in silicon carbide has been performed. A simple analytical expression, which links the degree of hexagonality of the polytype with the concentration of carbon and silicon vacancies, was obtained. The possible dependence of the model parameters on the experimental conditions is investigated.

Life Science Journal

Analysis of the national and foreign publications dedicated to the graphene production, its prope... more Analysis of the national and foreign publications dedicated to the graphene production, its properties study and graphene-based device prototyping. It is demonstrated that one of the most attractive devices for practical realization is a gas sensor based on the graphene film. Also it is demonstrated that a method of silicon carbide thermal decomposition is the advanced technology for the graphene electronics realization.

Materials Science Forum, 2004

ABSTRACT