The growth of GaS1-xSex films (0 <= x <= 1) on a sapphire substrate (001) was achieved through plasma-enhanced chemical vapor deposition, utilizing elemental precursors. The non-equilibrium low-temperature RF discharge plasma was the trigger for the chemical reactions that occurred during the deposition. The reactive components of the plasma formed in the gas phase were studied by means of optical emission spectroscopy. All deposited films were found to have a layered hexagonal structure with preferential orientation (004) and were characterized by linearly increasing lattice parameters with increasing selenium content (x). A shift of the out-of-plane vibration modes was observed in the Raman spectra. The films exhibit high transparency, with values approaching 70 %, in the 500-2500 nm region. The samples of GaS1-xSex luminesce from the blue to the red visible region, depending on their composition. It has been demonstrated that the substitution of sulfur for selenium results in a regular shift of the band edge and photoluminescence peaks to the long-wavelength region. The dependences of the surface morphology and conductivity on the composition were non-monotonic. The photosensitivity of the GaS1-xSex films gradually increases with increasing selenium content, and pure gallium selenide has the maximum photoresponse. The comprehensive study of GaS1-xSex films across the full compositional range allows to broadly consider them as a potential candidate for optoelectronic applications.

Iron-doped cadmium sulfide films (Fe-CdS) were produced by spray pyrolysis using iron nitrate, chloride and sulfate as iron precursors. Based on experimental analysis data and thermodynamic calculations, it was found that the composition, uniformity and surface morphology of the films significantly depend on the nature of the iron precursor. It has been found that all synthesized Fe-CdS films can be used as master alloys for the manufacture of Fe:ZnSe laser elements.

This study examines the specific characteristics of Raman scattering observed in ZnSnN2 samples produced via magnetron co-sputtering. The spectra demonstrate a high degree of similarity to the phonon density of states. This phenomenon is caused by the presence of Sn-Zn substitutional defects, which disrupt the ideal crystal structure and generate so-called defect-induced Raman modes across the entire first Brillouin zone. An increase in the elemental content of Sn leads to a decrease in the intensity of the 230 cm-(1) and 660 cm-(1) peaks and to their broadening. This suggests an intensification of the disorder within the cation sublattice. Following annealing at 450 degrees C in a vacuum, an increase in the intensity of the peaks at 450 cm-(1) and 560 cm-(1), as well as the Boson peak, was observed. We attribute these changes to the increased formation of Zn-N-Sn bonds within the film structure due to the ordering of the anion (nitrogen) sublattice. However, zinc and tin atoms still occupy random positions in their sublattices, contributing to the overall increase in structural disorder.

The properties of multilayer (up to 80 layers) nanoperiodic (period up to ~12 nm) Al 2 O 3 /Ge and Al 2 O 3 /Si/Ge/Si systems annealed in a nitrogen atmosphere at temperatures from 700 to 900°C are studied using transmission electron microscopy, X-ray techniques of photoelectron spectroscopy, diffractometry, and reflectometry, and optical methods of photoluminescence and Raman scattering. In Al 2 O 3 /Ge samples annealed at 700°C, the formation of Ge nanocrystals with a size of ~3 nm is detected, which disappear at 800–900°C, when nanocrystals of the Al 6 Ge 5 semiconductor phase of large size (>100 nm) grow. The introduction of separating layers of Si (Al 2 O 3 /Si/Ge/Si) leads to the formation of nanocrystals of the SiGe x alloy at a temperature of 800°C, above which the size of the crystallites of this phase is about ~3–4 nm. The data obtained using X-ray techniques are in good agreement with the results of high-resolution transmission electron microscopy and Raman spectroscopy. In the Al 2 O 3 /Ge samples, photoluminescence is observed at room temperature at ~2.1 eV, and in the Al 2 O 3 /Si/Ge/Si samples, there is an additional luminescence peak at ~1.4 eV. Hydrogenation of the samples by annealing in a hydrogen atmosphere at 500°C enhances the luminescence intensity.

Annealing of amorphous TiOx films obtained by electron-beam evaporation under atmospheric conditions at temperatures from 300 to 400°C is found to lead to the formation of an anatase crystalline phase. According to Raman spectroscopy data, the increase in the fraction of the the crystalline phase stops at an annealing temperature above 350°C. According to the results of X-ray phase analysis, the average crystallite diameter is about 23 nm. Electron microscopy studies have shown that, upon annealing, the near-surface layer (15 nm thick) crystallizes in the films, and TiO2 nanocrystals with sizes from 4 to 10 nm are formed in the bulk. As the depth increases, the number of nanocrystals decreases.

The annealing of amorphous TiO x films obtained by electron-beam evaporation under atmospheric conditions at temperatures from 300 to 400°C is found to lead to the formation of an anatase crystalline phase. According to Raman spectroscopy data, the increase in the fraction of the crystalline phase stops at an annealing temperature above 350°C. According to the results of X-ray diffraction analysis, the average crystallite diameter is about 23 nm. Electron-microscopy studies show that, upon annealing, the surface layer (15 nm thick) crystallizes in the films, and TiO 2 nanocrystals with sizes from 4 to 10 nm are formed in the bulk. As the depth increases, the number of nanocrystals decreases.

Zinc tin nitride (ZnSnN2, ZTN) films synthesized by magnetron co-sputtering at a temperature close to the ZTN decomposition point and with the cation ratio close to stoichiometric have been studied to gain insight into their structural, optical and electrical properties. According to X-ray diffraction and Raman spectroscopy, the samples are polycrystalline with some disorder in the cation sublattice. Hall effect measurements reveal n-type conductivity and very high carrier density above 10(19) cm(-3). At the lowest carrier density, the mobility achieves the best value similar to 19 cm(2)/(V*s), which is acceptable for device applications. The optical band gap shows a blue shift with increasing electron density, which is related to the increase in tin content and the Burstein-Moss effect. Analysis of the blue shift in terms of the Burstein-Moss effect theory gives a value of 1.43 eV for the intrinsic band gap of ZTN in the mixed-phase state.

The crystallinity of the tungsten (W) phase was improved with an increase in the thickness of this layer in the periodic W/Si multilayer structure. Both the α - and β -W phases were grown simultaneously and the contribution of these phases was modified by a change in the thickness of the W layers. For thinner W layers, the thermodynamically metastable β -W phase dominated, and with an increase in thickness, this phase was suppressed and the stable α -W phase became prominent. The crystallite size of these phases was almost linearly proportional to the thickness of the W layers in the multilayers. With the increase in thickness of Si layers in multilayers, Raman scattering showed a decrease in the bond-angle deviation of Si–Si bonding in the amorphous Si phase. The study revealed ordering of Si–Si bonding in the amorphous phase of Si with an increase in thickness of these layers in periodic W/Si multilayers.

A new method of forming the β-FeSi 2 phase on silicon and sapphire substrates by pulsed laser deposition in vacuum is considered. A series of structures is prepared with variations in the iron content in the target to be sputtered. The phase composition of films is analyzed by identifying peaks in the Raman spectra. The magnetic properties of samples are studied by recording the magnetic-field dependence of their Hall resistance. It is shown that the additional Fe 3 Si and FeSi phases are formed under conditions of growth that provide the more efficient inclusion of Fe atoms in the growing layer. Phase analysis of the films formed on silicon and sapphire substrates at identical technological parameters of growth is carried out.

In the article, we present and discuss the features of the structure and photoluminescence properties of Yb-doped As-S films synthesized by PECVD employing solid-state initial precursors. The doping was carried out during the deposition process. By controlling the temperature of the precursor sources and the composition of the low-temperature nonequilibrium plasma, we synthesized amorphous As-S:Yb films with Yb content ranging from 0.6 to 8.4 at. %. The change in the ratio of structural elements and surface morphology as a function of the elemental composition is shown. The increase of the Yb content leads to a redshift of the short-wavelength absorption edge. The dependence of the shape and intensity of F-2(5/2) -> F-2(7/2) photoluminescence, observed in the range 930-1030 nm on the excitation wavelength (632.8 nm and 785 nm) and Yb concentration was evaluated. The relation between composition and atomic structure of the amorphous matrix of arsenic sulfide on the photoluminescent properties of Yb3+ ions is discussed.

Raman scattering studies were carried out for the investigation of bonding and microstructural properties of dimensionally confined nanoscale Be layers in the periodic Mo/Be and Be/Mo multilayer st...

Structural changes under the action of Al+ irradiation have been investigated by X-ray diffraction for polymorphic Ga2O3 layers grown by halide vapor phase epitaxy on c-plane sapphire and consisting predominantly of alpha-phase with inclusions of e(x)-phase. As a result of irradiation, some new reflections appear, which can be interpreted in two ways - either as a phase transition of the alpha- and/or e(x)-phase to the more stable 8-phase, or as a selective radiation-stimulated strain of the e(x)-phase, i.e., an increase in the interplanar distance of a family of planes parallel to the surface. The discussed ion-stimulated phenomena have to be taken into account when utilizing ion implantation to modify Ga2O3 properties.

The paper considers a new method for the formation of the β-FeSi2 phase on silicon and sapphire substrates by pulsed laser deposition in vacuum. A series of structures with varying iron concentration in the sputtered target was prepared. The phase composition of the films is analyzed from the identification of peaks in the Raman spectra. The study of the magnetic properties of the samples was carried out by recording the magnetic field dependence of the Hall resistance. The formation of additional magnetic phases Fe3Si and FeSi is shown under growth conditions that provide an increased incorporation of Fe atoms into the formed layer. The analysis of the phase composition of films formed on silicon and sapphire substrates with the same technological growth parameters is carried out.

In this work a new plasma-based approach to hydrogen intercalation of Graphene grown on SiC is demonstrated. By optimization of the inductively coupled plasma parameters the intercalated by hydrogen Graphene has been modified gradually and transformed into the two-dimensional hydrocarbon Graphane. The intermediate stages during the transition of Graphene to Graphane were studied by means of Raman spectroscopy and AFM. The dependence of the intensities of the Raman Graphene fingerprints: D and G peaks on the hydrogen intercalation time has been studied. The changes of resistance during the hydrogen plasma treatment were parsed. The Raman (D + D ') peak corresponding to hydrogenated graphene was studied in detail. The method developed is highly reliable and flexible as well as convenient for large-scale fabrication of Graphane to be employed as a hydrogen storage material and in 2D electronics.

In periodic W/Be multilayers, thickness-dependent microstructural and phase modifications were investigated in W and Be layers. In X-ray diffraction, α-W was predominant for the ultrathin layer of W, while β-W evolved along with the α-W phase for higher film thickness. For the thicker layers, the thermodynamically metastable β-W vanished and a single well-defined preferably oriented stable α-W phase was observed. The lattice spacing revealed that these phases exist in the tensile stressed condition. With the increase in thickness of Be layers, the blueshift and narrow linewidth of the transverse optical (TO) phonon mode was observed in Raman scattering studies. However, the TO mode was redshifted and the linewidth was further narrowed consistently with an increase in the thermal annealing temperature of the multilayers. The investigation has quantified an increase in compressive strain and reduction of defects with an increase in thickness of the Be layers. However, for thermally annealed samples, the compressive strain in the Be layers was relaxed and crystalline quality was improved.

By using the spray pyrolysis technique, CdS films uniform in composition and structure with different contents of chromium and indium ions were deposited on quartz substrates. Their structure, optical properties, and surface morphology were investigated. Employing the films as dopant sources, a correlation has been revealed between the composition of the films and the content of optically active centers in bulk ZnSe samples after doping at the HIP treatment. The process of Cr2+ ions diffusion in polycrystalline zinc selenide was studied, concentration profiles were measured, and the diffusion coefficients of Cr2+ions in one-side doped CVD-ZnSe samples were determined.

The phonon and plasmon excitations and electronic properties of interfaces of periodic W/Si and Si/W multilayer structures were investigated. The Boson band originated from quasilocal surface acoustic phonons for ultrathin Si layers, excited by Raman scattering. In confined Si layers, a small fraction of crystalline Si nanoclusters were embedded within a large volume fraction of amorphous Si (a-Si) nanoclusters. The size of the a-Si nanoclusters was smaller for the thinner Si layer in the periodic layers. The plasmon energy in the Si layer was blueshifted with a decrease in the thickness of this layer. This was explained by the size-dependent quantization of plasmon shift. The valence band spectra comprised a substantial fine structure, which is associated with the interaction of valence orbitals of the W and Si atoms at the interface boundaries. For thinner Si layers, the binding interaction of W5d and Si3p states leads to the splitting of the density of states near the Fermi level in the energy range of 1.5-5 eV. However, the energy splitting with two maxima was observed at 0.7 and 2.4 eV for thicker layers. Thus, the results of X-ray photoelectron spectroscopy have indicated that the interface of W/Si multilayers consists of metal-enriched tungsten silicide. Both the atomic structure and the elemental composition of the silicide were modified with a change in the thickness of the Si layers. This novel investigation could be essential for designing nanomirrors with higher reflectivity.

Physical properties and stress analysis of Si layers embedded in bi-layer periodic Mo/Si and W/Si multilayer mirrors operating in extreme ultraviolet and X-ray region of wavelengths were investigated by Raman scattering. The study showed that alternate Si layers in these multilayers were exist in the amorphous phase. This was determined from the peak shift and linewidth of the transverse optical (TO) phonon mode. This mode was blueshifted with an increase in the thickness of amorphous Si (a-Si) layers embedded in the Mo/Si multilayers and redshifted upon thermal annealing. In contrast, the redshift of this mode in a-Si with an increase of thickness was observed for W/Si multilayers, and blueshifted upon thermal annealing. The behavior of the TO phonon mode of a-Si was also influenced by the microstructure of metallic layers and the composite stress of multilayers. Thermally annealed multilayers showed a reduction of the period thickness due to defect annihilation of a-Si layers which lead to the change of reflection properties of mirrors.

Microstructural investigation of the Mo/Si nanoscale multilayers (MLs) is essential to design high-reflective nanomirrors. Raman spectroscopy showed existence of silicon layer in the amorphous structure. Small fraction of the nanocrystalline silicon (nc-Si) phase was found to be embedded in the amorphous silicon (a-Si) matrix. The disorder in a-Si is increased with the decrease in the thickness of silicon layer in the Mo/Si MLs, determined by the increased bond-angle deviation (Delta Theta) of the Si-Si network. The MLs exposed to high-temperature (HT) showed a decrease in the Delta Theta value, which signifies the relaxation of both molecular disorder and residual stress. X-ray diffraction analysis confirmed the polycrystalline bcc phase of Mo and the formation of intermetallic t-Mo5Si3 phase in the interfaces. This phase is more prominent for higher value of beta (thickness ratio of high atomic weight (z) layer to ML period d, i.e. beta = d(Mo)/d). Intensity of the Mo (110) plane is decreased for the sample annealed at HT, which is directly related to the degree of amorphization and the formation of intermetallic phases. However, HT annealed Mo/Si showed the growth of Mo (220) planes for higher beta value of MLs. Current findings revealed that the disorder in the a-Si and microstructure of the Mo and intermetallic phase depend on the annealing temperature and the beta value. The analysis of the intermetallic phase is critical for the development of high reflective mirrors.

Structures with Ge/Si nanoparticles (quantum dots) in an aluminum-oxide matrix are of interest due to the combination of two basic semiconductors and the use of a matrix with a high permittivity and strong oxygen–metal bonding. In this study, multilayer nanoperiodic structures in the form of a substrate/Al 2 O 3 /Ge/Si/Al 2 O 3 …Al 2 O 3 sequence of layers (with the period Al 2 O 3 /Ge/Si and the number of periods up to 20) are produced and then annealed at different temperatures. It is shown that, after annealing, the structures contain both Ge and Si crystalline particles, whose dimensions and number are defined by the deposited-layer thicknesses and the annealing temperature. The results obtained by different optical techniques suggest that the structures exhibit the quantum-confinement effect. This inference is supported by high-resolution microscopy.