A comparative analysis of radiation-induced defect formation in the gallium and nitrogen sublattices of gallium nitride is conducted under irradiation by 15-MeV protons and 0.9-MeV electrons. Numerical modeling using the SRIM software is performed for proton deceleration, while analytical calculations are applied for electrons. The analysis shows that, under proton irradiation, the total vacancy-generation rate in the gallium sublattice ηFP(Ga) is approximately 560 cm–1, while in the nitrogen sublattice, ηFP(N) is approximately 1340 cm–1. Detailed numerical calculations using the Full Cascade mode indicate that the vacancy-formation rate due to protons in the gallium sublattice is 110 cm–1, with an additional 450 cm–1 generated by cascade processes. In the nitrogen sublattice, this disparity is even more pronounced, with 60 cm–1 attributed to direct proton interaction and 1280 cm–1 to cascade processes. Under electron irradiation, the vacancy-generation rate in the gallium sublattice ηFP(Ga) is approximately 4.7 cm–1, while in the nitrogen sublattice, ηFP(N) is approximately 2.0 cm–1. For the experimental study of radiation-induced defects in n-GaN, which create deep levels and compensate for the material’s conductivity, the forward current–voltage characteristics of Schottky diodes based on n-GaN are recorded. The analysis demonstrates that the charge-carrier removal rates in n-GaN are 0.47 cm–1 under electron irradiation and 150 cm–1 under proton irradiation. A comparison of the calculated and experimental parameters of radiation-induced defect formation provides insights into the compensation mechanism and the radiation-induced defects responsible for this process.

Imprinting magnetism into graphene makes an important step to its applications in spintronics. An actively explored approach is proximity coupling of graphene to a 2D magnet. In these endeavors, the use of epitaxial graphene may bring significant advantages due to its superiority over the exfoliated counterpart and natural integration with the substrate but the problem of attaining magnetism persists. Here, we report synthesis and analysis of a heterostructure coupling epitaxial graphene with a regular lattice of magnetic atoms formed by Eu intercalation. The magnetization measurements reveal easy-plane 2D magnetism in the material, with the transition temperature controlled by low magnetic fields. The emerging negative magnetoresistance and anomalous Hall effect point at spin polarization of the carriers in graphene. In the paramagnetic phase, the magnetoresistance in graphene exhibits critical exponential behavior of the induced magnetic state. The intercalation does not compromise the parental electronic structure - quantum oscillations in the resistivity manifest low-mass carriers in graphene. The results are set against those for an isostructural material based on intercalated nonmagnetic Sr. Overall, the study expands the family of 2D magnets and establishes a prospective material for graphene-based spintronics.

An approach of direct bonding of SiC wafers of differing polytypes has been implemented in order to create a template for cubic 3C-SiC homo epitaxy. Hetero epitaxial 3C-SiC layers grown by chemical vapor deposition were transferred onto a hexagonal 6H-SiC wafer. The results of structural characterization showed that the quality of 3C-SiC sublimation epitaxy on the templates is comparable to the level of epitaxy of cubic silicon carbide by chemical vapor deposition method. It was confirmed that the 3C-SiC layer transferred onto the 6H-SiC substrate plays the role of a crystalline “seed” that determines cubic polytype of the overgrown SiC layer.

Objective. To develop technique immobilizing antibodies graphene surface of proteins that play a significant role in pathogenesis Alzheimer's disease.Materials and methods. Graphene films were obtained sublimation surface of SiC substrates. Presence graphene monolayer was confirmed spectroscopy spectra. Graphene surface quality was evaluated cyclic voltammetry. Functionalization by amino groups was carried out method based on sorption pyrene derivatives from a solution and phenylnitrogroups electrochemical method. Graphene was kept in solutions monoclonal antibodies to human beta-amyloid peptide 1–42. Preparations were also kept in solution secondary antibodies labeled with FITZ. Results were evaluated fluorescence microscopy. Additionally, samples were kept in solution antibody with peroxidase label, which was detected chemiluminescence.Results. For attachment specific antibodies surface of graphene, quality its surface is great importance. Optimal working concentration of antibodies of human beta-amyloid 1–42 in solution for subsequent manufacture biological sensors is 15 micrograms per 1 ml. Covalent crosslinking antibodies with glutaraldehyde with amino groups on graphene gives a slight gain in the level fluorescence compared with noncovalent sorption on graphene with nitro groups. Functionalization phenylnitrogroups is optimal for further work related to the identification specific antigens.Conclusions. The technique of immobilization on the graphene surface of specific antibodies to beta-amyloid in concentrations detected by fluorescence microscopy and chemiluminescence is investigated. Amount antibodies sufficient to create a biosensor is immobilized on graphene. It was found that functionalization of phenylnitrogroups allows creating optimal conditions for the attachment of antibodies to the graphene surface, as well as washing resulting antibody-antigenic complexes for further reuse of graphene biosensors.

The atom/graphene/substrate system is considered and a scheme for obtaining analytical expressions for the adatom occupation numbers is proposed. The possibility of the presence of a gap in the electronic spectrum of graphene was taken into account. Simple and transition metals and semiconductors were considered as substrates, and simple theoretical models were used to describe their densities of states.

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 175°C). The blocking voltage of the diodes under study, Ub, was 600 and 1700 V. For devices with Ub = 600 V, the fluence range was 5 × 1013–1 × 1014 cm–2; for devices with Ub = 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.

Within the framework of the previously proposed model (S.Yu. Davydov. Phys. Solid State 64, 2018 (2022)), in which the interaction of a macromolecule (MM) with single-layer graphene (SLG) is carried out by stitching of dangling MM bonds with carbon atoms, the effect of these stitching on the mobility of carriers in graphene was studied. It is shown that short-range scattering of MM-SLG stitching prevails over Coulomb scattering. It has also been found that the effect of induced by stitching graphene deformation on mobility can be neglected compared to short-range scattering. The cases of free and epitaxial graphene are considered. The use of the MM-SLG-substrate structure as the basis of a biosensor is discussed.

The effect of high-temperature electron and proton irradiation on the characteristics of devices based on SiC has been studied. For the study, industrial 4H-SiC integrated Schottky diodes with an n-type base with a blocking voltage of 600, 1200, and 1700 V manufactured by CREE are used. Irradiation is carried out by electrons with an energy of 0.9 MeV and protons with an energy of 15 MeV. It is found that the radiation resistance of SiC Schottky diodes under high-temperature irradiation significantly exceeds the resistance of diodes under irradiation at room temperature. It is shown that this effect arises due to the annealing of compensating radiation defects under high-temperature irradiation. It is revealed that this effect arises due to the annealing of compensating radiation defects under high-temperature irradiation. The parameters of radiation defects are determined by the method of transient capacitance spectroscopy. Under high-temperature (“hot”) irradiation, the spectrum of radiation-induced defects introduced into SiC differs significantly from the spectrum of defects introduced at room temperature. The radiation resistance of silicon and silicon carbide is compared. The relatively small difference in the rate of carrier removal in SiC and Si upon irradiation at room temperature is due to the fact that in SiC, in contrast to Si, there is practically no annealing of primary radiation defects during irradiation.

Proton irradiation of β-Ga2O3 crystals has been established to lead to a significant increase in the amount of Cr3+ ions being active in luminescence. Using angle-resolved luminescence, the features of the spectra of Cr3+ ions were studied. The high sensitivity of photoluminescence spectra and the related selection rules to the local symmetry of Cr3+ ions in the β-Ga2O3 matrix has been found. The results obtained indicate the potential possibility of using β-Ga2O3 crystals as optical dosimeters of proton irradiation.

The properties of graphene chips with low reproducibility (LR) after photolithography (PLG) and graphene functionalization have been studied. It is shown that the introduction of additional cleaning after PLG can significantly increase the reproducibility of the parameters of processed graphene in biosensors. The use of dilute PBS solutions for virus detection makes it possible to increase the relative concentration sensitivity of biosensors by several times.

Mechanical stress in the surface layers of silicon wafers subjected to a bending mode of central symmetry is investigated by Raman spectroscopy. An original setup for bending wafers makes it possible to simultaneously take optical measurements on the stretched and compressed sides of silicon wafers. On the stretched and compressed sides of the silicon wafers used in this work, the mechanical stress produces an elastic deformation of 0.42% and 0.18%, respectively.

The simulation results of the temperature distribution in the growth area of graphene layers obtained by the method of thermal decomposition of the silicon carbide surface substrates in setup with induction heating are presented. The heating parameters of the setup elements are calculated using the commercial package COMSOL Multiphysics taking into account the electrical, thermal and magnetic properties of the materials from which the growth plant elements are made. A numerical estimate of the heating inhomogeneity of silicon carbide plates over its area during the growth of graphene layers at a given temperature is given. It is shown that the lateral temperature distribution over the area of the plate has radial symmetry with decreasing values towards the center.

BSTS epitaxial thin film topological insulators were grown using the MBE technique on two different types of substrates i.e., Si (111) and SiC/graphene with Bi0.7Sb1.6Te1.8Se0.9 and Bi0.9Sb1.5Te1.8Se1.1, respectively. The crystallographic properties of BSTS films were investigated via X-ray diffraction, which showed the strongest reflections from the (0 0 l) facets corresponding to the rhombohedral phase. Superior epitaxial growth, homogeneous thickness, smooth surfaces, and larger unit cell parameters were observed for the films grown on the Si substrate. Polarization dependent Raman spectroscopy showed a weak appearance of the A(g) mode in cross--polarized geometry. In contrast, a strong E-g mode was observed in both parallel and cross-polarized geometries which correspond to the rhombohedral crystal symmetry of BSTS films. A redshift of A(g) and E-g modes was observed in the Raman spectra of BSTS films grown on the Si substrate, compared to those on SiC/graphene, which was directly associated with the unit cell parameter and composition of the films. Raman spectra showed four fundamental modes with asymmetric line shape, and deconvolution of the peaks resulted in additional modes in both the BSTS thin films. The sum of relative ratios of linewidths of fundamental modes (A(g) and E-g) of BSTS films grown on Si substrate was lower, indicating a more ordered structure with lower contribution of defects as compared to BSTS film grown on SiC/graphene substrate.

The processes of long-term (persistent) conductivity relaxation in n-type silicon carbide irradiated with protons in a wide range irradiation temperatures Ti from 23 to 500°C are studied. It is shown for the first time that as a result of the proton irradiation with the fluence of 1014 cm–2, two “competing” long-term processes of conductivity relaxation can be observed. The characteristics of both processes significantly depend on the irradiation temperature and bias, at which the dynamics of conductivity changes is studied. After applying a relatively small constant voltage to the sample, the decrease in current during persistent relaxation process is replaced by persistent increase in current and establishing of the steady state. Both processes are characterized by a very wide range of time constants. When irradiation is performed at room temperature (Ti = 23°C), the time constants range from milliseconds to hundreds of seconds. When the samples are irradiated at elevated temperatures, the time constants are in the range from milliseconds to hundreds of milliseconds. The higher the bias applied, the faster the decrease in current is replaced by its increase. The possible nature of the observed effects is discussed.

The carrier removal rates during proton and electron irradiations of n-type GaN grown by metal-organic vapor phase epitaxy were determined. Irradiation was carried out with protons with energy of 15 MeV in the fluence range 0 ≤ Фр ≤ 5 × 1014 cm–2; the range of fluences when irradiated with electrons with energy of 0.9 MeV was 0 ≤ Фn ≤ 5 × 1016 cm–2. The value of the removal rate during proton irradiation, ηp ≈ 140 cm–1, is close to the lower limit of currently known values of ηp and indicates a sufficiently high level of radiation resistance of the studied material with respect to proton irradiation. The rate of carrier removal under the influence of electron irradiation, ηe is ≈0.47 cm–1 and corresponds to the typical values of ηe for type gallium nitride obtained by various methods.

The well-known effect of the local interaction between graphene and photoresist (LIGF) during the creation of biosensors is shown to lead to non-uniform distribution of compressive stresses, which deteriorates the adsorption properties of graphene, parameter reproducibility, and detecting ability of influenza B and SARS-Cov-2 biosensors. It is also shown that controlling the occurrence of LIGF areas on a graphene surface by atomic force microscopy or introducing a protective layer between graphene and photoresist can minimize the non-persistent effect of LIGF. The results of influenza B and SARS-CoV-2 imaging on the graphene surface in biosensor chips in a scanning electron microscope are presented.

At present, intensive research is underway in the field of vacuum-sublimation growth of 3C-SiC. Transfer of a thin (001)3C-SiC layer onto a 6H-SiC wafer is a promising way to fabricate a 3C-SiC/6H-SiC substrate for growing device-quality homoepitaxial films of low defect density. The article presents the results of the structural characterization of an interface formed during the transfer of a 3C-SiC layer onto a 6H-SiC(0001) wafer, performed with transmission electron microscopy (TEM). A 3C-SiC film with a thickness of about 10 mu m, grown by chemical vapor deposition (CVD) on a Si(001) substrate, was utilized in the study. Silicon acted as a bonding material in the transfer process. The morphology and microstructure of the interface between a 6H-SiC substrate and a 3C-SiC (001)-oriented layer are under consideration. TEM investigation reveals an effect of "self"-orientation of the layer with respect to the wafer during the transfer process: an interaction between the molten silicon layer and silicon carbide throughout crystallization results in the generation of defined orientation relationships with respect to substrate axes. An analysis of selected area electron diffraction patterns taken from interfaces showed the relationships to be 3C-SiC{001} & Vert; 6H-SiC(0001) and 3C-SiC < 11((sic)) 0 > similar to & Vert; 6H-SiC < 11 2((sic))0 >.

Electronic structures of superlattices and encapsulated layers are obtained by Green’s function metho d. The simple scheme for estimation of interlayer charge transfer is proposed. As an example, layers of graphene and graphene-like compounds are considered.

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.

The quality of graphene intended for use in biosensors was assessed on manufactured chips using a set of methods including atomic force microscopy (AFM), Raman spectroscopy, and low-frequency noise investigation. It is shown that local areas of residues on the graphene surface, formed as a result of the interaction of graphene with a photoresist at the initial stage of chip development, led to a spread of chip resistance (R) in the range of 1–10 kOhm and to an increase in the root mean square (RMS) roughness up to 10 times, which can significantly worsen the reproducibility of the parameters of graphene chips for biosensor applications. It was observed that the control of the photoresist residues after photolithography (PLG) using AFM and subsequent additional cleaning reduced the spread of R values in chips to 1–1.6 kOhm and obtained an RMS roughness similar to the roughness in the graphene film before PLG. Monitoring of the spectral density of low-frequency voltage fluctuation (SU), which provides integral information about the system of defects and quality of the material, makes it possible to identify chips with low graphene quality and with inhomogeneously distributed areas of compressive stresses by the type of frequency dependence SU(f).