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Aim. To evaluate the effectiveness of antibacterial treatment of root canals in chronic apical periodontitis with an erbiumchromium laser.Materials and methods. Group I consisted of 16 patients – antibacterial treatment of root canals was carried out with 10 ml of 3% solution of sodium hypochlorite «Belodez». Group II – 29 patients – antibacterial treatment was carried out with an erbium-chromium laser Waterlase MD in the following mode: wavelength – 2780 nm, power – 1.5 W, pulse duration – 140 μs, frequency – 40 Hz. Antibacterial efficacy was assessed by the results of microbiological studies of samples from the root canal before and after antibacterial treatment. Results. During antibacterial treatment with an erbium-chromium laser, a statistically significant decrease in the concentration of Escherichia coli, Staphylococcus aureus, Moraxella lacunata, Actinomyces israelii, Streptococcus mutans, Corynebacterium xerosis occurred in comparison with the control group.Conclusions. The dynamics of clinical signs in patients of the two groups indicates the anti-inflammatory effect of the Waterlase MD erbium-chromium laser, which confirms a pronounced antibacterial effect against Escherichia coli, Corynebacterium xerosis, Actinomyces israelii, Streptococcus mutans, Staphylococcus aureus, Moraxella lacunata.

It is shown that the degree of damage of the near-surface layer of p-silicon can be estimated with the aid of a MoOx/p-Si selective contact, the current–voltage characteristics of which are highly sensitive to states on the silicon surface formed during the deposition of silicon oxide by method of magnetron sputtering.

It is shown for the first time that thin boron phosphide (BP) layers on silicon substrates can be formed by low-temperature plasma-enhanced atomic layer deposition at 250°C. Experiments demonstrated the possibility of using these BP/Si interfaces as selective hole contacts to silicon in solar cells.

Use of inorganic oxides as transport layer material is a promising way to increase the efficiency of perovskite solar cells. Results of the studies of the influence of the gas mix composition in the plasma discharge used during magnetron sputtering on the optical, electrical, and structural parameters of deposited thin nickel oxide films are reported. Addition of oxygen or nitrogen to pure argon atmosphere (up to 30 vol %) was shown to change the growth rate (1.2–2.3 nm/min), resistivity of the samples (8.5–208 Ω cm), material band gap (2.85–3.43 eV), and the spectral dependence of the extinction coefficient, while the structural and morphological parameters of synthesized thin films were not affected. The lowest extinction coefficients were found in films deposited in pure argon atmosphere, which determines the capabilities of their usage in photovoltaic converters based on perovskite compounds.

The lattice-matched GaP/Si superlattice is proposed to be used as an active material for top junction, which is grown on n–GaP/p-Si heterojunction bottom sub cell. Computer simulations demonstrate that GaP/Si structures with 1-2 nm Si quantum wells allow one to obtain a material with an effective band gap of 1.4–1.6 eV. GaP/Si nanostructures were grown at 380 °C by plasma deposition using PE-ALD and PECVD for GaP and Si layers growth, respectively. Structural, optical and electrical properties of GaP/Si nanostructures grown on Si and GaP wafers are reported and discussed in terms of photovoltaic application.

The results of studying the applicability of various etchants for the precision wet etching of structures of monolithic optoelectronic devices containing GaPNAs layers are presented. It is shown that an etchant based on potassium iodide and hydrochloric acid is best suited for this purpose. The presence of nitrogen (up to 4%) and arsenic in the semiconductor composition does not greatly affect the etchant action but requires additional calibration experiments to refine the etching rate in each particular case. Examples of the practical application of precision etching to measure the characteristics of GaPNAs-based solar cells are presented.

The influence of hydrogen plasma treatment on electrical and optical properties of the vertical GaN nanowires (NWs)/Si heterostructures synthesized via plasma assisted molecular beam epitaxy is studied. The effect of the treatment is thoroughly studied via variation of the passivation duration. Photoluminescence (PL) investigation demonstrates that the passivation affects the doping of the GaN NWs. The samples were processed as photodiodes with top transparent electrode to obtain detailed information about the n-GaN NWs/p-Si heterointerface under illumination. Electron beam induced current (EBIC) measurements demonstrated the absence of the potential barriers between active parts of the diode and the contacts, indicating ohmic behavior of the latter. I-V characteristics obtained in the dark and under illumination show that hydrogen can effectively passivate the recombination centers at the GaN NWs/Si heterointerface. The optimum passivation duration providing improved electrical properties is found to be 10 minutes within taken passivation regimes. It is demonstrated that the longer treatment causes degradation of the electrical properties. The discovered phenomenon is discussed in details.

International audience; Dilute nitrides lattice-matched to GaP were studied to explore the possibilities to improve their properties by additional indium or arsenic content in the GaPN alloy for further utilization in solar cells. Admittance spectroscopy shows that intrinsic layers of GaPNAs and InP/GaPN grown by molecular-beam epitaxy have unintentional background silicon donor doping. Deep-level transient spectroscopy allowed us to reveal several defect levels. In GaPNAs, two defect levels were detected at Ec − 0.58 eV and Ev + 0.44 eV, with respective concentrations of 4 × 1015 cm−3 and 2 × 1015 cm−3. After thermal annealing, these could be reduced by a factor of two and by more than one order of magnitude, respectively, leading to an increase of external quantum efficiency and open-circuit voltage of solar cells. The InP/GaPN layer exhibits a defect level at Ec − 0.44 eV (with a concentration of 2 × 1014 cm−3), which is of similar nature as the one at Ec − 0.58 eV in GaPNAs. Furthermore, unlike in GaPNAs, defect levels close to midgap were also detected in the InP/GaPN layer. These non-radiative recombination centers lead to poorer photoelectric properties of solar cells based on InP/GaPN as compared to those based on GaPNAs. Therefore, the introduction of arsenic in the compound and post-growth thermal annealing allowed us to reduce the defect concentrations in dilute nitrides and improve photoelectrical properties for photovoltaic applications.

Copper (I) oxide and zinc oxide films are formed on silicon and glassy quartz substrates by magnetron assisted sputtering. The thickness of the films is tens and hundreds of nanometers. The films are grown at different substrate temperatures and different oxygen pressures in the working chamber. The film samples are studied by the X-ray diffraction technique, scanning electron microscopy, and optical methods. It is established that an increase in the substrate temperature yields a change in the surface morphology of copper (I) oxide films towards the formation of well-pronounced crystallites. The reflectance and Raman spectra suggest that the quality of such films is close to that of bulk Cu2O crystals produced by the oxidation of copper. As concerns ZnO films, an increase in the substrate temperature and an increase in the partial oxygen pressure make it possible to produce films, for which a sharp exciton structure is observed in the reflectance spectra and the emission of excitons bound at donors is observed in the luminescence spectra.

Microcrystalline gallium phosphide (GaP)/Si multilayer structures grown on GaP substrates using combination of plasma enhanced atomic layer deposition (PE-ALD) for GaP and plasma-enhanced chemical vapor deposition for Si layers deposition are studied by three main space charge capacitance techniques: capacitance versus voltage (C-V) profiling, admittance spectroscopy (AS) and deep level transient spectroscopy (DLTS), which have been used on Schottky barriers formed on the GaP/Si multilayer structures. C-V profiling qualitatively demonstrates an electron accumulation in the Si/GaP wells. However, quantitative determination of the concentration and spatial position of its maximum is limited by the strong frequency dependence of the capacitance caused by electron capture/emission processes in/from the Si/GaP wells. These processes lead to signatures in AS and DLTS with activation energies equal to 0.39 ± 0.05 and 0.28 ± 0.05 eV, respectively, that are linked to the energy barrier at the GaP/Si interface. It is shown that the value obtained by AS (0.39 ± 0.05 eV) is related to the response from Si/GaP wells located in the quasi-neutral region of the Schottky barrier, and it corresponds to the conduction band offset at the GaP/Si interface, while DLTS rather probes wells located in the space charge region closer to the Schottky interface where the internal electric field yields to a lowering of the effective barrier in the Si/GaP wells. Two additional signatures were detected by DLTS, which are identified as defect levels in GaP. The first one is associated to the SiGa + VP complex, while the second was already detected in single microcrystalline GaP layers grown by PE-ALD.

The article is based on an important characterization task to accurately evaluate the properties of the layers, their interfaces with c-Si, and to select the best candidates to integrate them into a c-Si-based solar cell. The work has shown that GaP could be doped with n-type doping, thus providing a selective contact for the electrons, and has a significant valence band offset with c-Si, making it an excellent candidate as a selective contact, without requiring an additional ITO layer.

This work is devoted to the study of the deposition of a-Si:H by the PECVD method in continuous and pulsed regime on test structures in the form of trenches with a high aspect ratio. The thicknesses of the layers obtained in these modes were investigated by the method of scanning electron microscopy. It was shown that the layers obtained in the pulsed mode, as compared with the continuous one, have better conformity.

In this work last results on optimization of (p)a-Si:H/p-Si ohmic contact made by PECVD method are presented. A strong effect of growth temperature and trimethylboron flow on charge carriers transport was demonstrated. An optimized (p)a-Si:H layer also was successfully applied as an emitter layer to a heterojunction solar cell fabrication where a measured open circuit voltage of 0.65 V was obtained.

InGaN/GaN nanorod structure is presented for the fabrication of light-emitting diodes by means of plasma-chemical etching. Processes of the etching of nanorods and the defect passivation in a planar InGaN/GaN quantum dot heterostructure are studied. The obtained results allow creating the light-emitting diode nanostructure with a greater efficiency compared to the classical planar technology.

In this work the properties of the BP/Si heterojunction interface were investigated by capacitance methods, the deep levels transient spectroscopy method and admittance spectroscopy. Admittance spectroscopy did not detect any defects, but the deep level transient spectroscopy showed response with activation energy of 0.33 eV and capture cross-section σn=(1-10)·10-19 cm2 and defect concentration (NT) is in the order of 1013 cm-3. This defect level is a trap for electron with position of 0.33 eV below the conduction band in region near the BP/Si interface.

This article is devoted to the formation and study of the properties of amorphous gallium phosphide layers obtained by plasma-chemical deposition at a temperature of 250 °C. The optical and structural properties of the obtained layers on fused silica and silicon substrates were investigated. The possibility of the formation of a homogeneous amorphous gallium phosphide with a smooth surface at a low temperature and low power of RF plasma was shown.

The new design for full silicon multi-junction solar cells, which consists of combination of silicon nanowires (SiNWs) and conventional silicon-based hetero-junctions, is proposed in the paper. A top junction is based on SiNWs covered by a-Si:H p-i-n structures while bottom junction is based on amorphous/crystalline silicon (a-Si:H/c-Si) hetero-junctions. Vertically-aligned design of top p-i-n junction is a way to enhance absorption in a-Si:H without rising its thickness and therefore it allows one to increase short circuit current. This is a key issue for current match with bottom a-Si:H/c-Si heterojunction. Silicon wires of submicron diameters and micron length are formed by etching. A cost effective technology to form the periodic SiNWs on the silicon front surface was developed based on dry plasma etching using submicron size polystyrene spheres as a mask. A significant photocurrent increase was experimentally demonstrated for a-Si:H p-i-n top sub-cells deposited on SiNWs. While bottom a–Si:H/c–Si heterojunction sub-cells formed on the surface with SiNWs demonstrate strong light trapping effect, which leads to enhanced external quantum efficiency in the long wavelength region compared to planar reference cell.

Nanoscale copper (I) oxide layers are formed by magnetron-assisted sputtering onto glassy and silicon substrates in an oxygen-free environment at room temperature, and the structural and optical properties of the layers are studied. It is shown that copper oxide formed on a silicon substrate exhibits a lower degree of disorder than that formed on a glassy substrate, which is supported by the observation of a higher intensity and a smaller half-width of reflections in the diffraction pattern. The highest intensity of reflections in the diffraction pattern is observed for Cu2O films grown on silicon at a magnetron power of 150 W. The absorption and transmittance spectra of these Cu2O films are in agreement with the well-known spectra of bulk crystals. In the Raman spectra of the films, phonons inherent in the crystal lattice of cubic Cu2O crystals are identified.

We report the possibility of autocatalytic synthesis of highly crystalline perfect CdTe nanowires by magnetron presputtering deposition through the windows in ultrathin layers of SiO2. The photoluminescence spectra of obtained CdTe nanowires exhibit an emission band in the 1.4–1.7 eV region, indicating crystalline perfection of the nanowires.

International audience; The properties of n‐GaP/p‐Si interface as well as their influence on solar cell performance are studied for GaP layers grown by low‐temperature (380 °C) plasma‐enhanced atomic layer deposition (PE‐ALD). The influence of different plasma treatments and RF power values are explored. The increase of RF power leads to a growth transition from amorphous (a‐GaP) to microcrystalline GaP (μc‐GaP) with either amorphous‐GaP/Si or epitaxial‐GaP/Si interface, respectively. However, when continuous hydrogen plasma is used the amorphous‐GaP/Si interface exhibits better photovoltaic performance compared to the epitaxial one. Values of open circuit voltage, Voc = 0.45–0.55 V and internal quantum efficiencies, IQE > 0.9 are obtained for amorphous‐GaP/Si interfaces compared to Voc = 0.25–0.35 V and IQE

The paper presents the results of the study of the effect of plasma etching of n-type silicon spin-coated with polystyrene balls on bulk silicon properties using careful surface chemical treatments and passivation. Plasma etching was carried out under different substrate temperatures (up to -140 °C). Photoluminescence decay time imaging was used to evaluate effective carrier lifetime in silicon samples after dry etching and a-Si:H passivation. According to the results obtained, plasma etching of n-Si(100) spin-coated with polystyrene balls within the temperature up to -140 °C in gas mixture of SF6/O2, RF and ICP plasma power of 30 W and 1000 W, respectively leads to minority carrier lifetime decrease. The difference in the rate of carrier lifetime degradation with etching time was found.

InGaN/GaN QDs nanorod structure for the fabrication of light-emitting diodes by means of plasma-chemical etching is presented. Processes of the etching of nanorods and the defect passivation are studied. The obtained results can be used to create the light-emitting diode nanostructure with a greater efficiency compared to the classical planar technology.

Fabrication of hybrid micro- and nanostructures with a strong nonlinear response is challenging and represents a great interest due to a wide range of photonic applications. Usually, such structures are produced by quite complicated and time-consuming techniques. This work demonstrates laser-induced hybrid metal-dielectric structures with strong nonlinear properties obtained by a single-step fabrication process. We determine the influence of several incident femtosecond pulses on the Au/Si bi-layer film on produced structure morphology. The created hybrid systems represent isolated nanoparticles with a height of 250–500 nm exceeding the total thickness of the Au-Si bi-layer. It is shown that fabricated hybrid nanostructures demonstrate enhancement of the SHG signal (up to two orders of magnitude) compared to the initial planar sample and a broadband photoluminescence signal (more than 200 nm in width) in the visible spectral region. We establish the correlation between nonlinear signal and phase composition provided by Raman scattering measurements. Such laser-induced structures have significant potential in optical sensing applications and can be used as components for different nanophotonic devices.

The formation of p-type GaP by plasma-enhanced atomic layer deposition at a temperature of 380 °C has been studied. The incorporation of Zn impurity was detected by the method of glow discharge optical emission spectroscopy (GDOES). Strong band bending was confirmed by electrical measurements performed for the p-n homojunctions formed by deposition of p-GaP on the surface of n-type GaP substrates, which indicates the acceptor behavior of the impurity. It has been shown that p-type GaP deposited by PE-ALD can be used to form photovoltaic converters.

III-V nanowires (NWs) are a promising technology for piezotronic and nanooptoelctronic applications. In this work, we investigate the processes of fabricating a structure with InP NW arrays on a silicon substrate for piezotronic applications. The coating of the NW array with a polymer and the fabrication of a transparent electrical contact to NWs is studied. The piezoelectric effect for the structures with a nonzero piezoelectric modulus d 33 is demonstrated in an oil environment at voltage amplitudes of about 100 mV. The experimental electromechanical coupling is about 0.049, which is close to the theoretical estimate of 0.053.

This article is concerned with plasma-enhanced atomic layer deposition of GaPN in the form of a GaP/GaN digital alloy at 380°C on a silicon substrate. It was found that the GaP/GaN digital alloy has a uniform structure without significant mechanical stresses and defects at the interface with the substrate. EDX and Raman scattering study confirmed deposition of a monolithic GaPN crystalline material with a total nitrogen content of 7.8%.

The author analyzes the main tools for promoting scientific articles that are used most often by the editorial board of the Computer Optics journal to promote the publication in international scientometric databases and popularize the ideas of science. It is noted that the use of these tools allowed the publication to increase significantly the “portfolio” of articles, the number of articles published per year, including the articles in English, increase significantly the citation of journal articles in other scientific publications, as well as expand the geographical spread of authors.

Arrays of silicon nanowires were fabricated by dry etching in the ICP mode in a mixture of SF6/O2 gases at a temperature of-140 °C. Defects located near the wafer surface with E a =0.30 eV, σ=(1–10)×10−14 cm2 and E a =0.68–0.74 eV, σ=1×10−15 cm2 were detected by admittance spectroscopy and deep-level transient spectroscopy. An increase in the dry etching time from 3.5 min (for the 1st sample) to 4.5 min (for the 2nd sample) leads to an rise of their concentration, but additional stage of wet etching in 4% KOH during 30 s leads to a vanish of the response from the first sample (N T ˂1011 cm−3), while for the second sample the defect concentration becomes in two times lower.

In this work an application of selective contacts p-Si/MoOx for evaluation of silicon surface degradation is shown. Using a method of I-V measurements the effect of silicon surface degradation during SiO2 magnetron deposition was demonstrated.

Periodic nanoheterostructures GaP/Si grown by PE-ALD with argon plasma treatment on GaP wafers were studied by capacitance methods. The response from silicon quantum well was clearly observed by capacitance-voltage characteristics as peak on profile of concentration of free charge carriers in sample GaP (50 cycles)/Si (22 s) with 7 wells. It is explained by higher doping of GaP layers due to higher total time of silane flow in growth process unlike samples with smaller numbers of silicon wells or lower time of silicon deposition. Further, response from defect level was observed with capture cross-section (1–10)×10−15 cm−2, and its energetic level decreases from 0.51 eV to 0.39 eV under conduction band with increasing of total time of silane flow.

The work is devoted to the study of electrical properties of InGaN nanostructures with branched morphology (NSs) on p-type Si substrates. It was found that the IV curves between InGaN NSs and p-Si are close to linear, which could indicate a tunneling conductivity. Such unique structures as InGaN NSs on p-Si can be used as building blocks for water splitting devices and tandem solar cells.

The features of the formation of a SiO2 hard mask using dry etching and nanosphere lithography are considered in the paper. A series of experiments was carried out using a variation of plasma etching parameters such as ICP and RF power, pressure as well as a substrate temperature. As a result, optimal parameters were found to obtain both good selectivity and high etching rate.

In this paper, we study the effect of the height and diameter of vertically aligned silicon structures on their optical properties. Structures with different geometry were formed using nanosphere lithography and dry etching. Nanosphere lithography was realized with 0.9 and 2 μm latex spheres. The etching process was carried out through a formed mask (template) composed of 0.9 and 2 μm latex spheres, respectively. The diameter of the spheres and the etching time determined the size of the formed structures and their optical properties. A significant reduction of the total reflection with height as well as blue shift of the minimum with diameter decrease were observed.

In this article the temperature dependences of selective contacts based on MoOx were studied. The p-Si/MoOx/Al structure was fabricated. Current-voltage and capacitance-voltage characteristics in the temperature range from 80 to 300K were measured. Band diagram was also calculated to reveal potential barriers location and its influence on charge carrier transport.

The work is devoted to exploration of arrays of vertical aligned silicon nanowires (SiNWs) obtained by cryogenic dry etching in ICP mode with height of 4.5-5.5 μm and aspect ratio of 7. It was shown that geometry of nanowires has crucial influence on rate of wet etching in KOH since it is higher for 3D objects than for planar wafer, and the diameter should be the same along the nanowire for controlled wet etching. Wet etching in 4% KOH solution during 30 s allowed to save array of uniformity vertical aligned SiNWs with height of 4 μm and diameter of 500 nm. Such treatment reduced concentration of defects detected by deep-level transient spectroscopy, particularly, it drops as minimum in two times for deep level with £0=0.68-0.74 eV placed near to surface of wafer.

Using methods of numerical simulation, the modes of operation are considered and structures are determined for solar cells of combined dimension based on a planar GaPNAs/Si heterostructure and an array of GaN nanowires. It is shown that the array of GaN nanowires features antireflective properties at a level no lower than 2.5% under illumination with the AM1.5D solar spectrum. The efficiency of solar cells is affected to the greatest extent by the lifetimes of minority charge carriers and the thickness of photoactive layers. It is demonstrated that the efficiency of two-junction solar cells composed of GaPNAs alloy layers and an array of GaN nanowires on a Si substrate can be as high as 32% for AM1.5D.

Design and operation modes of double-junction monolithic lattice-matched solar cells based on the ZnSiP2/Si system of materials have been calculated. The effect of the photoactive region thickness and minority carrier lifetime in ZnSiP2 layers on the efficiency of conversion of the incident solar light energy into electrical power was determined. It is shown that solar cells based on ZnSiP2/Si heterostructures can provide efficiencies of 28.8% at AM1.5D, 100 mW/cm2, and 33.3% at AM1.5D, 200 W/cm2.

An approach for epitaxial growth of GaP layer on Si substrate at low temperature (380°C) by plasma-enhanced atomic layer deposition (PEALD) is explored. A significant improvement of the crystalline properties of the GaP layers was obtained using additional in-situ Ar plasma treatment. The epitaxial growth for the first 20-30 nm of GaP on the Si substrate could be achieved according to transmission electron microscopy. Moreover, use of in-situ Ar plasma treatment during PEALD process allows one to increase the growth rate per cycle from 0.9±0.1 A/cycle to 1.9±0.1 A/cycle and reduce RMS roughness from 3.76 nm to 1.88 nm. The effect of Ar plasma treatment on the electronic properties of the GaP/Si interface is studied by deep level transient spectroscopy (DLTS). A defect level at (0.33±0.03) eV below the conduction band is observed in the underlayer of Si for the GaP/Si structure grown under Ar plasma treatment. However, the defect response observed by DLTS vanishes after rapid thermal annealing at 500 oC in nitrogen ambient.

The effect of hydrogen plasma treatment on the electrical and optical properties of GaN NWs/Si based vertical hetero structures synthesized by the method of plasma molecular beam epitaxy is studied. The effect of treatment has been carefully studied by variation of the passivation duration. Measurements of the electron beam-induced current (EBIC) technique showed the absence of potential barriers between the active parts of the diode and the contacts, which indicates the ohmic behavior of the latter. The current - voltage characteristics show that hydrogen can efficiently passivate recombination centers at the GaN NWs/Si heterointerface. It is established that the optimal passivation duration, providing improved electrical properties, is 10 minutes in the adopted passivation modes. It is shown that a longer treatment causes a deterioration in electrical properties.

The work is devoted to studying the influence of an additional step of argon plasma treatment on the quality of the GaP/n-Si isotype heterojunction grown by plasma-enhanced atomic-layer deposition (PE-ALD). Deep-level transient spectroscopy measurements demonstrated that argon plasma leads to the formation of defects with a high concentration in silicon wafers, unlike the PE-ALD mode without a step of hydrogen or argon plasma treatment. In addition, GaP layers obtained by PE-ALD have defects with an activation energy of 0.40 eV and 0.62 eV for processes with and without argon plasma treatment, respectively.

The experimental and modelling results of the investigation of photovoltaic properties of the InP nanowires grown on p-Si substrate are presented. It is shown that InP 2D-layer between nanowires on Si is II-type heterojanction. The resulting structure exhibits an open-circuit voltage (Voc) of 0,37 V, a short-circuit current density (Jsc) of 10.6 mA/cm2, a fill factor (FF) of 0.61 and efficiency of 2.4% at 1 sun. The InP/p-Si structure can be applied as prototype for solar cells or the photosensitive component in an integrated circuit based on silicon technology.