Objectives: Nanocomposite films based on Ag-Si compounds have application in many areas of science and technology. However, their manufacturing process can be accompanied by the formation of silicides and metastable phases. In this connection, the task of developing methods for their identification arises. In this work, we attempted to solve this task using X-ray diffraction, ultra-soft X-ray emission spectroscopy, and theoretical calculations of the electron density of states for an Ag55Si45 film obtained by ion-beam sputtering of a composite target. Experimental: As a result of comprehensive studies, a nanogranular structure of the film was revealed, with an average silver particle size of ~15 nm, separated by a matrix based on phases of amorphous silicon a-Si, SiO2, and suboxide SiO1.3, as well as a silver silicide phase. A comparison of the experimental Si L2.3 X-ray emission spectrum of the Ag55Si45 film with theoretically calculated spectra of the AgSi3, Ag2Si, and Ag3Si phases shows the best agreement with the spectrum of the Ag2Si phase. Moreover, the Ag2Si phase was detected in the works of other authors. Conclusions: Thus, based on X-ray diffraction, X-ray emission spectroscopy, and theoretical calculations of the electronic density of states, it has been established that a metastable Ag2Si phase is formed in the Ag55Si45 film produced by ion-beam sputtering

A central challenge in spintronics is the development of materials for efficient spin-polarized current generation. While crystalline Heusler alloys often fall short of predicted half-metallicity due to structural disorder, their amorphous analogs present a promising avenue. In this work, we investigate how the composition-dependent structural evolution of short-range order controls room temperature electronic transport in amorphous FexSi1−x (0.44 ≤ x ≤ 0.75) alloy thin films. This structural evolution, revealed by X-ray reflectivity, underpins a transition from hopping to metallic conduction across distinct amorphous phases (FeSi → Fe2Si → Fe3Si). In the FeSi-like phase region, electronic transport is governed by Mott variable-range hopping, resulting in high resistivity and low Hall mobility. The onset of metallic conduction within the amorphous Fe2Si- and Fe3Si-like composition ranges yields lower resistivity alongside enhanced hole mobility. Our results establish a direct structure-property relationship in amorphous FexSi1−x alloys, demonstrating the ability to selectively design electronic transport through fine compositional tuning. Understanding the interplay between local atomic order and electronic transport in amorphous Fe–Si alloys provides key insights for engineering next-generation spintronic devices.

This work describes the synthesis characteristics of GaN layers using plasma-assisted molecular beam epitaxy on Si (111) substrates, without employing the substrate nitridation procedure or forming an intermediate Al-containing layer. It was found that in GaN layers grown directly on the Si substrate, after passivating its surface with Ga atoms, the residual stress values remain consistent across different layers of the epitaxial film. Additionally, GaN exhibits a high packing density of crystallites on the surface, indicated by a smaller block size, which is associated with a high density of dislocations at the grain boundaries. The introduction of an additional indium flux as a surfactant during the growth of the GaN layer results in the formation of InxGa1-xN solid solution regions on the surface of an amorphous SixNy sublayer sublayer, which is formed between between the nanocolumns during the growth of of the nucleation layer. In this case, scenario, gradient distribution of residual stresses stresses is observed the depth of the GaN film film, decreasing it approaches the surface). surface. The results demonstrate using proposed technology it enables the growth of films with stable optical properties, properties without the formation of cracks in the epitaxial film.

Nanostructured composite films based on Ag-Si containing silver nanoparticles are used as a material for SERS (Surfaceenhanced Raman spectroscopy) substrates, plasmonic back reflector, nanoplasmonic sensors, nonlinear optics devices, memristor structures, etc. Due to the widespread use of nanocomposite films based on Ag-Si, there is a need to develop simple and affordable methods for their production compatible with semiconductor technology. Therefore, this work is devoted to the production of an Ag80Si20 nanocomposite film with a high silver content (80 at.%) by ion-beam sputtering with simultaneous control of the morphology, structure, phase composition and electrical properties of the manufactured sample. As a result of complex studies using X-ray diffraction, ultra-soft X-ray emission spectroscopy, SEM and AFMmicroscopy, it was found that the film is a nanocomposite material based on silver nanoparticles with an average size of ~15÷30 nm. At the same time, some silver nanoparticles are in direct contact, while some Ag nanoparticles are isolated from each other by a shell of silicon dioxide SiO2 and amorphous silicon a-Si. Such a nanogranulated structure of the Ag80Si20 film causes the presence in the test sample of the effect of switching from a high-resistance state (880 Ohm) to a lowresistance state (~1 Ohm) under the action of a voltage of ~ 0.2 V. As a result of the formation of conductive filaments (CF) of Ag atoms in the dielectric layer between the silver granules

Based on X-ray reflectometry and ultrasoft X-ray spectroscopy data, the opportunity of controlling surface porosity using multi-stage electrochemical etching modes is presented. It is presented how, with an increase in the porosity index of the near-surface layer, the morphology changes and the degree of oxidation of multilayer porous silicon samples increases.

Porous silicon (por-Si) is a complex multiphase material, the composition and functional properties of which greatly depend on the features of its formation. In this work, samples of porous silicon with porosity indices from 5 to 80% are obtained by electrochemical etching and their photoluminescence properties are studied. The porosity of the samples is varied by changing the current density of electrochemical anodization during the etching process. The porosity index is calculated according to the X-ray reflectometry method. The aim of our work is to establish correlations between the porosity index, composition, intensity, and mechanism of porous-silicon photoluminescence. The surface composition is controlled by ultrasoft X-ray spectroscopy and infrared spectroscopy. An increase in the degree of oxidation of the surface of the samples with an increase in the porosity index is shown. Two well-known mechanisms of porous silicon photoluminescence associated with the composition and morphology of the surface are found, and it is established at which porosity values they prevail. It is shown that an increase in the porosity index leads to an increase in the intensity of photoluminescence.

Наноструктурированные композитные пленки на основе Ag-Si, содержащие наночастицы серебра, используются в качестве материала SERS-подложек (Surface-enhanced Raman spectroscopy), плазмонных отражателей, наноплазмонных сенсоров, устройств нелинейной оптики, мемристорных структур и т. д. Широкое применение нанокомпозитных пленок на основе Ag-Si приводит к необходимости развития простых и доступных методов их получения, совместимых с полупроводниковой технологией. Поэтому настоящая работа посвящена получению нанокомпозитной пленки Ag80Si20 с высоким содержанием серебра (80 ат. %) методом ионно-лучевого распыления с одновременным контролем морфологии, структуры, фазового состава и электрических свойств получаемого образца. В результате комплексных исследований рентгеновской дифракции, ультрамягкой рентгеновской эмиссионной спектроскопии, РЭМ и АСМ микроскопии установлено, что пленка представляет собой нанокомпозитный материал на основе серебряных наночастиц со средним размером ~15÷30 нм. При этом некоторые наночастицы серебра находятся в непосредственном контакте, в то время как часть Ag наночастиц изолированы друг от друга оболочкой из диоксида кремния SiO2 и аморфного кремния a-Si. Такая наногранулированная структура пленки Ag80Si20 обуславливает наличие в исследуемом образце эффекта переключения из высокоомного состояния (880 Ом) в низкоомное (~1 Ом) под действием напряжения ~0.2 В в результате образования проводящих мостиков (филаментов) из атомов Ag в слое диэлектрика между серебряным гранулами

Al1-xSix films were obtained by ion beam sputtering of an Al-Si composite target. Studies of the structure and electronic structure of Al1-xSix films were carried out. The structure and electronic structure of the films were investigated. The formation of an ordered phase of Al3Si was detected using X-ray diffraction and X-ray emission spectroscopy, as well as theoretical calculation of the band structure and Si L2.3-, Al L2.3-spectra. It is established that the Al3Si phase has a Cu3Au (Pm3m) type structure with a lattice parameter a=4.085 angstrom, the primitive sublattices of which are filled with atoms of two types Al and Si. It was found that the long-range order in Al1-xSix ion-beam films is sufficiently resistant to changes in the elemental composition from Al0.75Si0.25 to Al0.55Si0.45.

The influence of Ar + SiH4 + O2 plasma formulation on the phase composition and optical properties of amorphous SiOx films with silicon nanoclusters obtained using PECVD with DC discharge modulation was studied. Using a unique technique of ultrasoft X-ray emission spectroscopy, it was found that at a 0.15 mol.% plasma oxygen content, amorphous silicon a-Si films are formed. At a high oxygen content (≥21.5 mol.%), nanocomposite films based on SiOx silicon suboxide containing silicon nanoclusters ncl-Si are formed. It was found that the suboxide matrix consists of a mixture of SiO1.3 and SiO2 phases, and the average oxidation state x in the SiOx suboxide matrix is ~1.5. An increase in the concentration of O2 in the reactor atmosphere from 21.5 to 23 mol.% leads to a decrease in ncl-Si content from 40 to 15% and an increase in the average oxidation state x of SiOx from 1.5 to 1.9. In this case, the suboxide matrix consists of two phases of silicon dioxide SiO2 and non-stoichiometric silicon oxide SiO1.7. Thus, according to the experimental data obtained using USXES, the phase composition of these films in pure form differs in their representation in both random coupling and random mixture models. A decrease in the ncl-Si content of SiOx films is accompanied by a decrease in their sizes from ~3 to ~2 nm and a shift in the photoluminescence band from 1.9 eV to 2.3 eV, respectively.

Porous silicon samples with a porosity index of 5% to 80% were obtained in the work by electrochemical etching and their photoluminescence properties were studied as well, Porosity index was calculated according to the data of X-ray reflectometry technique.Composition of the surface was controlled by ultra-soft X-ray spectroscopy and infrared (IR) spectroscopy. Degree of the sample surface oxidation was shown to be increased with the enhancement of porosity enhancement. Two known mechanisms of photoluminescence in porous silicon were detected related with a composition and morphology of its surface. It was found the values of porosity index specifying the dominations of these mechanisms. An increase of porosity index was shown to result in the enhancement of photoluminescence.

The aim of this work is a comprehensive study of the effect of variable atomic composition and structural-phase state of (CoFeZr)x(MgF2)100−x nanocomposites (NCs) on their nonlinear electronic and magnetic/magneto-optical properties. Micrometer-thick nanocomposite layers on the glass substrates were obtained by ion-beam sputtering of a composite target in the argon atmosphere in a wide range of compositions x = 9–51 at·%. The value of the resistive percolation threshold, xper = 34 at·%, determined from the concentration dependencies of the electrical resistance of NCs, coincides with the beginning of nucleation of metallic nanocrystals CoFeZr in MgF2 dielectric matrix. The absolute value of maximum magnetoresistance of NCs is 2.4% in a magnetic field of 5.5 kG at x = 25 at·%, up to the percolation threshold. Two maxima appear in the concentration dependencies of magneto-optical transversal Kerr effect, one of which, at x = 34 at·%, corresponds to the formation of CoFeZr alloy nanocrystals of a hexagonal structure, and the second one at x = 45 at·% corresponds to the phase transition of nanocrystals from a hexagonal to a cubic body-centered structure. The magnetic percolation threshold in (CoFeZr)x(MgF2)100−x system at xfm = 34 at·%, with the appearance of a hysteresis loop and a coercive force of Hc ≈ 8 Oe, coincides with the resistive percolation threshold xper = 34 at·%. Concentration dependence of the coercive force showed that at low contents of metallic alloy x < 30 at·%, NCs are superparamagnetic (Hc = 0). With an increase of the alloy content, in the region of magnetic and resistive percolation thresholds, NCs exhibit a magnetically soft ferromagnetic character and do not change it far beyond the percolation threshold, with the maximum value of the coercive force Hc < 30 Oe.

Porous silicon samples with a porosity index of 5% to 80% were obtained in this work by electrochemical etching, and their photoluminescence properties were also studied. The porosity index was calculated according to the data from X-ray reflectometry. The composition of the surface was controlled by ultra-soft X-ray spectroscopy and infrared (IR) spectroscopy. The degree of the sample surface oxidation increased with the porosity enhancement. Two known mechanisms of photoluminescence in porous silicon were detected that are related to the composition and morphology of its surface. The values of the porosity index specifying the dominations of these mechanisms were determined. Enhancement of photoluminescence was shown to be attributed to an increase in the porosity index.

The aim of this work was to comprehensively study the effect of the variable atomic composition and structural-phase state of Cox(MgF2)100-x nanocomposites on their nonlinear transport and magnetic/magneto-optical properties. Micrometer-thick nanocomposite layers on glass substrates were obtained by means of ion-beam sputtering of a composite target in the argon atmosphere in a wide range of compositions (x = 16–59 at.%). Using a low metal content in the nanocomposite, magnesium fluoride was kept in the nanocrystalline state. As the metal content increased, nanocrystalline cobalt was formed. The value of the resistive percolation threshold, xper = 37 at.%, determined from the concentration dependences of the electrical resistance of the nanocomposites coincided with the beginning of nucleation of the metallic nanocrystals in the MgF2 dielectric matrix. The absolute value of the maximum negative magnetoresistive effect in the nanocomposites was 5% in a magnetic field of 5.5 kG at a Co concentration of x = 27 at.%.

An experimental investigation of the structure and phase composition by X-ray, Raman, and ultrasoft X-ray emission spectroscopy, as well as the study of the electrical properties of WxSi(1-x) films used as sensitive elements of superconducting single-photon detectors (SNSPD), depending on the thickness in the range from 7 to 80 nm, was carried out, according to the results of which it was found that the W3Si phase is presumably formed in films 20 and 40 nm thick with a resistivity of 8.4 10-5 and 6.0 10-5 Ω cm, respectively, containing the WSi2, W5Si3, and SiO2 phases, as well as WOx and a small share of β-W. Films with a thickness of 7 nm have the highest resistivity of 18.0 10-5 Ω·cm and contain nanocrystals, WSi2, SiO2, as well as β-W, and an amorphous silicon phase. Films with a thickness of 80 nm (the resistivity is also 18.0 10-5 Ω·cm) predominantly contain WSi2, as well as W5Si3 and SiO2, and, presumably, the W3Si phase.

We present a combined investigation of the electronic structure of bulk arc-melted full-Heusler Co _2-x Fe _1+x Si ( x = 0, 0.5, 1) and CoFeSi alloys using density functional theory and ultrasoft X-ray emission spectroscopy. We perform first-principles calculations of the spin-polarized total and partial density of states for the Co and Fe 3 d ( s , p ) as well as for the Si 3 s ( p , d ) orbitals. It is demonstrated that only Co _2 FeSi alloy exhibits a half-metallic behavior. However, the inverse CoFe _2 Si alloy shows pseudogap and high spin polarization at the Fermi level. We carry out ultrasoft X-ray emission Si L_2,3 measurements, which provide the information about the local partial density of states of Si 3 s and 3 d orbitals in the valence band localized on Si atoms. We compare the measured spectra with our theoretical calculations and discuss them in terms of the contribution of s and d -electrons to the bonding. The Si and transition-metals sd and dd bonding formation is shown in the Co _2-x Fe _1+x Si and CoFeSi alloys. The high spin polarization values, along with the extremely high Curie temperature, make these compounds potential candidates for spintronic applications.

We carried out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen plasma activation on a hybrid substrate containing layers of silicon carbide and porous silicon. Using X-ray diffractometry, Raman and photoluminescence spectroscopy, it is shown that thin films formed on a hybrid substrate have minimal residual stresses and intense photoluminescence.

The growth of GaN films on preliminarily treated Si(001) substrates by chloride–hydride vapor-phase epitaxy through a buffer layer is reported. It is demonstrated that the use of the technology proposed in the study brings about the formation of a Si transition sublayer in the Si substrate, so that further growth on this sublayer provides the formation of columnar GaN grains, between which there is a thin interlayer of the AlN phase. The epitaxial GaN film possesses low residual stresses, which is reflected in high-intensity luminescence.

We present a combined investigation of the electronic structure of bulk arc-melted full-Heusler Co2-xFe1+xSi (x = 0, 0.5, 1) and CoFeSi alloys using density functional theory and ultrasoft X-ray emission spectroscopy. We perform first-principles calculations of the spin-polarized total and partial density of states for the Co and Fe 3d (s, p) as well as for the Si 3s (p, d) orbitals. It is demonstrated that only Co2FeSi alloy exhibits a half-metallic behavior. However, the inverse CoFe2Si alloy shows pseudogap and high spin polarization at the Fermi level. We carry out ultrasoft X-ray emission Si L-2,L-3 measurements, which provide the information about the local partial density of states of Si 3s and 3d orbitals in the valence band localized on Si atoms. We compare the measured spectra with our theoretical calculations and discuss them in terms of the contribution of s and d-electrons to the bonding. The Si and transition-metals sd and dd bonding formation is shown in the Co2-xFe1+xSi and CoFeSi alloys. The high spin polarization values, along with the extremely high Curie temperature, make these compounds potential candidates for spintronic applications.