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The goal of the RENEB inter-laboratory comparison 2021 exercise was to simulate a large-scale radiation accident involving a network of biodosimetry labs. Labs were required to perform their analyses using different biodosimetric assays in triage mode scoring and to rapidly report estimated radiation doses to the organizing institution. This article reports the results obtained with the cytokinesis-block micronucleus assay. Three test samples were exposed to blinded doses of 0, 1.2 and 3.5 Gy X-ray doses (240 kVp, 13 mA, ∼75 keV, 1 Gy/min). These doses belong to 3 triage categories of clinical relevance: a low dose category, for no exposure or exposures inferior to 1 Gy, requiring no direct treatment of subjects; a medium dose category, with doses ranging from 1 to 2 Gy, and a high dose category, after exposure to doses higher than 2 Gy, with the two latter requiring increasing medical attention. After irradiation the test samples (no. 1, no. 2 and no. 3) were sent by the organizing laboratory to 14 centers participating in the micronucleus assay exercise. Laboratories were asked to setup micronucleus cultures and to perform the micronucleus assay in triage mode, scoring 500 binucleated cells manually, or 1,000 binucleated cells in automated/semi-automated mode. One laboratory received no blood samples, but scored pictures from another lab. Based on their calibration curves, laboratories had to provide estimates of the administered doses. The accuracy of the reported dose estimates was further analyzed by the micronucleus assay lead. The micronucleus assay allowed classification of samples in the corresponding clinical triage categories (low, medium, high dose category) in 88% of cases (manual scoring, 88%; semi-automated scoring, 100%; automated scoring, 73%). Agreement between scoring laboratories, assessed by calculating the Fleiss' kappa, was excellent (100%) for semi-automated scoring, good (83%) for manual scoring and poor (53%) for fully automated scoring. Correct classification into triage scoring dose intervals (reference dose ±0.5 Gy for doses ≤2.5 Gy, or reference dose ±1 Gy for doses >2.5 Gy), recommended for triage biodosimetry, was obtained in 79% of cases (manual scoring, 73%; semi-automated scoring, 100%; automated scoring, 67%). The percentage of dose estimates whose 95% confidence intervals included the reference dose was 58% (manual scoring, 48%; semi-automated scoring, 72%; automated scoring, 60%). For the irradiated samples no. 2 and no. 3, a systematic shift towards higher dose estimations was observed. This was also noticed with the other cytogenetic assays in this intercomparison exercise. Accuracy of the rapid triage modality could be maintained when the number of manually scored cells was scaled down to 200 binucleated cells. In conclusion, the micronucleus assay, preferably performed in a semi-automated or manual scoring mode, is a reliable technique to perform rapid biodosimetry analysis in large-scale radiation emergencies.

The doping of dilute nitrides is an important point of the growth and processing technology for different optoelectronic devices based on these compounds. In this paper, both intentional and nonintentional doping of InGaAsN and GaAsSbN have been investigated by temperature-dependent Hall effect measurements. Dilute nitrides layers have been grown by low-temperature (Tcryst < 600 °C) liquid-phase epitaxy (LPE). The chemical elements Sn and Mg have been chosen as n-type and p-type dopants, respectively. All nominally undoped InGaAsN layers are n-type with free carrier concentration about one order of magnitude higher than layers not containing nitrogen and grown by LPE. This makes it difficult to obtain epitaxial layers with p-type conductivity with these compounds. However, high-quality n-type, p-type and nearly compensated GaAsSbN layers have been successfully grown covering a large range of carrier concentrations from 1015 to 6×1018 cm−3. The quality of the GaAsSbN layers has been evidenced by a good photoresponse with a low energy threshold extended down to 1.2 eV as obtained by surface photovoltage spectroscopy.

We present an original study on quaternary GaAsSbN layers and multilayer heterostructures grown by low-temperature liquid-phase epitaxy (LPE) on GaAs substrates aiming to explore their potential for photovoltaic applications. We choose Sn and Mg as suitable dopants for practical use. Our experiments on doping reproducibly show the introduction of controlled concentrations of doping impurities in the range applicable to device fabrication. High-quality n-, p- and nearly compensated GaAsSbN layers covering a large range of carrier concentrations from 1015 to 6 × 1018 cm−3 have been grown at temperatures lower than 600 °C. The successful LPE growth of p-i-n GaAs/GaAsSbN/GaAs heterostructures based on closely compensated i-GaAsSbN is demonstrated for the first time. Temperature-dependent photoluminescence and room temperature surface photovoltage contactless characterization techniques have been used for investigation of the grown structures. These measurements have revealed high optical quality with a low concentration of localized states and red photoresponse limit extended down to 1.2 eV.

Importance: Sodium glucose cotransporter 2 inhibitors reduce morbidity and mortality in patients with heart failure and reduced ejection fraction (HFrEF). Clinicians may find estimates of the projected long-term benefits of sodium glucose cotransporter 2 inhibitors a helpful addition to clinical trial results when communicating the benefits of this class of drug to patients. Objective: To estimate the projected long-term treatment effects of dapagliflozin in patients with HFrEF over the duration of a patient’s lifetime. Design, Setting, and Participants: Exploratory analysis was performed of Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure (DAPA-HF), a phase 3 randomized, placebo-controlled clinical trial conducted at 410 sites in 20 countries. Patients with an ejection fraction less than or equal to 40% in New York Heart Association functional classification II to IV and elevated plasma levels of N-terminal pro B-type natriuretic peptide were enrolled between February 15, 2017, and August 17, 2018, with final follow-up on June 6, 2019. Mean (SD) duration of follow-up was 17.6 (5.2) months. Interventions: Dapagliflozin, 10 mg, once daily vs placebo in addition to standard therapy. Main Outcomes and Measures: The primary composite outcome was time to first hospitalization for heart failure, urgent heart failure visit requiring intravenous therapy, or cardiovascular death. The trial results were extrapolated to estimate the projected long-term treatment effects of dapagliflozin over the duration of a patient’s lifetime for the primary outcome and the secondary outcome of death from any cause. Results: A total of 4744 patients (1109 women [23.4%]; 3635 men [76.6%]) were randomized in DAPA-HF, with a mean (SD) age of 66.3 (10.9) years. The extrapolated mean event-free survival for an individual aged 65 years from a primary composite end point event was 6.2 years for placebo and 8.3 years for dapagliflozin, representing an event-free survival time gain of 2.1 years (95% CI, 0.8-3.3 years; P = .002). When considering death from any cause, mean extrapolated life expectancy for an individual aged 65 years was 9.1 years for placebo and 10.8 years for dapagliflozin, with a gain in survival of 1.7 years (95% CI, 0.1-3.3; P = .03) with dapagliflozin. Similar results were seen when extrapolated across the age range studied. In analyses of subgroups of patients in DAPA-HF, consistent benefits were seen with dapagliflozin on both event-free and overall survival. Conclusions and Relevance: These findings indicate that dapagliflozin provides clinically meaningful gains in extrapolated event-free and overall survival. These findings may be helpful in communicating the benefits of this treatment to patients with HFrEF. Trial registration: ClinicalTrials.gov Identifier: NCT03036124.

This paper reports on liquid phase epitaxy (LPE) growth and characterization of monocrystalline dilute nitride InGaAs(Sb)N and GaAsSbN layers in view of their photovoltaic applications. To obtain high quality epitaxial layers without phase separation the low-temperature variant of the LPE method is used. The structural characterization of the samples is carried out by means of scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction measurements. The optical bandgap is studied by photoluminescence (PL) spectroscopy at low and room temperature. Surface photovoltage spectroscopy (SPV) is applied to determine the optical absorption edge. Both PL and SPV spectra reveal a decrease of the band gap of GaAsSbN as compared to InGaAs(Sb)N, which is of value for its application in solar cells.

Dilute nitrides are semiconductor alloys, obtained from the conventional III-V compounds by incorporating a small amount of nitrogen. In this work, we focus on GaAsSbN considered as a perspective material for incorporation in multijunction solar cells. Nitrogen creates a localized level inside the conduction band continuum. The interaction of this level with the conduction band is usually described by the single band anti-crossing (BAC) model. The double BAC model of GaAsSbN considers both the N and the Sb localized levels in the conduction and the valence band, respectively. We calculate the bandgap energy of GaAsSbN employing the double BAC model for different concentrations of Sb and N. Parameters of the BAC model taken from different literature sources are used in the calculations and their influence on the final result is explored. Finally, the calculated bandgap energies are compared to experimental data of GaAsSbN layers grown on n-GaAs substrates by low-temperature liquid phase epitaxy. These data include the optical absorption edge of the material determined by surface photovoltage spectroscopy and the energy position of the photoluminescence peak at room temperature.

In this paper, we present a study on liquid phase epitaxy (LPE) grown dilute nitride GaAsSbN layers and p-i-n heterostructures for use in multijunction solar cells. The composition of the layers and chemical bonding of Sb and N in the compounds were determined by energy- dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The electrical properties of the grown samples were characterized by Hall effect measurements. Nominally undoped layers are n-type with Hall carrier concentration of 5 × 1016cm-3. Mg was successfully used as acceptor dopant for obtaining closely compensated layers with electron concentration of 1015 cm-3 as well as p-type layers with high free hole concentrations in the range (5-7) × 1018cm-3. Temperature-dependent photoluminescence spectra at low and high excitation were measured to evaluate the optical quality and identify localized states in the grown layers. Non-contact surface photovoltage method provided information about the absorption characteristics of the GaAsSbN layers. A series of GaAs/GaAsSbN/GaAs heterostructures based on closely compensated i-GaAsSbN have been also grown by LPE. The red limit of the structures determined from surface photovoltage measurements was extended down to 1.2 eV. Single junction p-i-n solar cells with area 0.16 cm2 were performed based on the grown structures. A power conversion efficiency of 4.1 % was measured for the fabricated cells under AM1.5 air global conditions.

In this paper, we present single heterojunction p-i-n GaAsSbN/GaAs solar cells grown by low-temperature liquid-phase epitaxy (LPE) – this is of interest as a component of multi-junction solar cell devices. The quaternary absorber layer was characterized by low excitation power photoluminescence to give the temperature dependence of the bandgap. This conformed to the Varshni function at low temperatures to within 10 meV, indicating relatively small alloy potential fluctuations. The absorption properties and the transport of the photogenerated carriers in the heterostructures were investigated using surface photovoltage method. A power conversion efficiency of 4.15% (AM1.5, 1000 W·m−2) was measured for p-i-n GaAsSbN/GaAs solar cells, which is comparable to the efficiency of MOCVD grown devices of this type. This is promising for the first report of LPE grown GaAsSbN/GaAs solar cells since the current record efficiency for the cells based on these compounds grown by MBE stands just at 6%. The long-wavelength photosensitivity of the cells determined from external quantum efficiency and surface photovoltage measurements was shown to be extended to 1040 nm.

We studied the growth temperature effect on nitrogen incorporation into GaAsN layers grown by liquid-phase epitaxy (LPE). The growth of dilute nitrides at nearly equilibrium conditions during LPE presents several major challenges: low solubility of nitrogen in Ga-melt, small incorporation efficiency in the solid and high volatility of nitrogen. GaAsN layers are grown from three different initial epitaxy temperatures: 580 °C, 680 °C and 780° C using GaN powder in the melt as a source of nitrogen. The N content in GaAsN is estimated from X-ray diffraction curves applying Vegard’s law. The local microstructure and surface morphology of the grown layers are studied by Fourier-transform infrared spectroscopy and atomic force microscopy measurements, respectively. The absorption edge and the composition dependence of the effective band gap are determined by employing optical transmission and surface photovoltage spectroscopies.

The papers in this special section focus on cardiovascular system monitoring and therapy. The number of devices for the measurement and interpretation of biological systems that describe performance of the cardiovascular system is growing. Among others, this is due to the improvement of circuit and system design that renders the devices wearable and easy to use. Moreover, internetworking enables these devices to exchange data. Their true impact on patient care is highly dependent on the quality and relevancy of the data acquired. The design of circuits and systems to answer the growing demand and the necessity to have portable and connected devices lead to a focus on designing ultra-low power apparatus, mixed-signal devices, using nanoscale electronics. Microelectronic issues are therefore at the heart of the demand. All this requires inter-disciplinary collaborations between scientists, engineers, medical researchers, and practitioners. The interconnection of these embedded devices, known as Internet of Things, is expected to usher in the medical field, among others to study the cardiovascular system of patients. Data processing and storage will also take place in the healthcare information technology. Furthermore, key issues such as data security and privacy will be determinants of the utility of these systems and impact in healthcare monitoring and management. This special issue aimed to provide a forum for both established experts and newinvestigators to share their developments, knowledge, and insights for the further design of circuits and systems aiming at being integrated in sensors to monitor or treat the cardiovascular system.

The present work focuses on reviewing the scientific literature on various types of tungsten-based glasses such as tungsten–phosphate, tungsten–tellurite, tungsten–borate glasses, tungsten–germinate, tungsten–antimonate, and non-traditional tungsten oxide-containing glasses. The glass formation, structure, thermal, some chemical, physical and characterization of materials are discussed. Tungsten-based glasses show a remarkable potential for many photochromic, electrochromic and gas sensing applications.

Dilute nitride InGaAsSbN layers grown by low-temperature liquid phase epitaxy are studied in comparison with quaternary InGaAsN layers grown at the same growth conditions to understand the effect of Sb in the alloy. The lattice mismatch to the GaAs substrate is found to be slightly larger for the InGaAsSbN layers, which is explained by the large atomic radius of Sb. A reduction of the band gap energy with respect to InGaAsN is demonstrated by means of photoluminescence (PL), surface photovoltage (SPV) spectroscopy and tight-binding calculations. The band-gap energies determined from PL and ellipsometry measurements are in good agreement, while the SPV spectroscopy and the tight-binding calculations provide lower values. Possible reasons for these discrepancies are discussed. The PL spectra reveal localized electronic states in the band gap near the conduction band edge, which is confirmed by SPV spectroscopy. The analysis of the power dependence of the integrated PL has allowed determining the dominant radiative recombination mechanisms in the layers. The values of the refraction index in a wide spectral region are found to be higher for the Sb containing layers.

New multicomponent (100 − (x − y))·(0.6B2O3·0.4Bi2O3)·xLa2O3·yWO3, x = 0, 10; y = 0 ÷ 40 mol% glasses were obtained by melt quenching technique and its structure were examined by infrared and Raman spectroscopies. Based on the obtained spectral data it was suggested that in the absence of La2O3, tungsten incorporates into boro-bismuthate network in small quantities through Bi3 + and В О W bonds are not formed. Accumulation of Bi O W bonds stimulates crystallization processes. La2O3 is crucial to connect tungstate units with boro‑bismuthate glass matrix and to realize amorphous network with their participation. It was supposed that in glasses with higher WO3 content (30 and 40 mol%) two inconsisted glass networks are formed bismuth-borate one built up by BO3, BO4, BiO6 units and tungstate one, built up mainly by WO6. These networks are interconnected through lanthanum.

In this paper, we present an original study on metamorphic GaAsSb layers grown by liquid phase epitaxy (LPE) on GaAs substrates for photovoltaic applications. To ensure a controlled growth of the layers with reproducible composition and properties a low-temperature (below 600 °C) variant of LPE was used combined with a precise choice of the technological conditions. This allowed obtaining layers with ∼8% Sb in the As sublattice. The crystal structure, composition, surface morphology, local arrangement and chemical bonding of Sb in the obtained layers were investigated by a variety of measurement methods including X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Hall-effect measurements were performed in the temperature range of 80–300 K to clarify the influence of defects on the transport properties. Temperature-dependent photoluminescence spectra at low excitation power were measured to evaluate the optical quality and identify localized states in the grown layers. The optical absorption properties and the transport of the photogenerated carriers in the grown samples were investigated using surface photovoltage (SPV) spectroscopy at room temperature. The SPV measurements have shown that the long-wavelength photosensitivity of the GaAsSb layers is extended down to 1.2 eV.

International audience; Glasses of (100 - (x + y))·(0.6B2O3·0.4Bi2O3)·xLa2O3·yWO3, x = 0, 10; y = 0 ÷ 40 mol% were prepared by melt quenching. Density measurements, thermal analysis, UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and theoretical modeling using Density Functional Theory were employed to identify the effect of WO3 content on the structural and physicochemical properties of these glasses. The glass transition temperature and density increase steadily with increasing WO3 content, most probably because of the formation of mixed Bi–O–W and La–O–W crosslinks. The lower band gap energy values show that the introduction of WO3 or La2O3 to 60B2O3·40Bi2O3 glass increases the number of non-bridging oxygen species in the glass structure. The photoelectron analysis aided by theoretical calculations discover that additionally to the tetrahedrally coordinated W ions, most of the existing WO6 octahedral units in glasses with nominal WO3 content below 20 mol% are distorted, leaving practically the tungsten ions in a quasi-tetrahedral coordination. At higher WO3 content (30–40 mol%) the concentration of octahedrally coordinated tungsten atoms dominate strongly over those of tetra- and quasi-tetra-coordinated W ions. Moreover, the comparison with appropriate crystal standards allows offering a complete description of the existing bridging and non-bridging linkages and their most likely O1s binding energies.

The effect of the addition of Nb2O5 to the WO3-La2O3-B2O3 glasses on their structure and physical properties (density, molar volume, glass transition temperature) has been investigated by using of IR and Raman spectroscopy, density measurement, and DTA analysis. Raman and IR spectra revealed that niobium ions incorporate into base tungstate glass matrix as NbO6 octahedra, interconnected by corners and edges. At lower Nb2O5 content (10 mol%), there is a high number of mixed B-O-Nb, and W-O-Nb bonds in the glass network. With increasing Nb2O5 concentration (15 mol% and 20 mo%), these bonds are gradually replaced by Nb-O-Nb linkages between corner shared NbO6 octahedra, forming 3D clusters, which are incorporated into amorphous network mainly trough La-O-Nb bonds. The addition of niobium oxide above 10 mol%, leads to decrease of the thermal stability of glasses and to increase in the density which is related with the formation of niobium oxide polyhedral clusters.

We report on LPE growth and characterization of dilute nitride InGaAs(Sb)N layers nearly lattice matched to GaAs. In order to obtain high quality epitaxial layers without phase separation low-temperature variant of LPE method has been used. The composition and crystalline quality of the grown InGaAs(Sb)N layers have been determined by energy dispersive X-ray microanalysis and X-ray diffraction methods. SEM and AFM measurements on grown samples revealed flat interfaces and surface roughness in the range 0.2 - 0.3 nm. In order to identify the N-bonding mechanism in the alloys and the nature of nitrogen related clusters IR absorption and Raman scattering spectroscopy have been applied. The optical band gap of the samples is studied by photoluminescence (PL) spectroscopy at low and room temperatures and by surface photovoltage (SPV) spectroscopy at room temperature. The SPV and PL spectra reveal a red shift of the absorption edge and PL peak position as compared to GaAs, as well as localized states near the conduction band minimum. However, the optical band gap bowing of the samples appears smaller with respect to the random alloy, which is explained by the short-range ordering favored by LPE growth at near-equilibrium conditions. Variable angle ellipsometry is applied to determine the spectral behavior of the complex refractive index and estimate the band gap energy of the samples.

Dilute nitride InGaAsN and GaAsSbN layers are grown by low-temperature liquid-phase epitaxy (LPE) on GaAs substrates and characterized in view of application in solar cells. The composition of the layers is determined by energy-dispersive X-ray spectroscopy. X-ray photoelectron spectroscopy measurements confirm the Sb content and provide information about the chemical bonding of the N atoms. The band gap values at room temperature assessed from surface photo-voltage and photoluminescence measurements are in good agreement. The experimental results show that the layers exhibit reproducible properties, including a good optical quality and a photosensitivity red limit extended in comparison to GaAs down to about 1.33 – 1.37 eV for InGaAsN and 1.19 – 1.23 eV for GaAsSbN layers. The results obtained highlight the capacity of the LPE for growing dilute nitride layers with good optical quality for photovoltaic applications.

In this paper, we report a novel route to obtain LiVMoO6 nanocrystals using a soft mechanochemical synthesis method. Powder X-ray diffraction, infrared, and Raman data indicated the formation of a single-phase LiVMoO6 with brannerite-type structure after 60-min milling time. The average particles size of the obtained LiVMoO6, derived from transmission electron microscopy data is about 46 nm. From UV–Vis diffuse reflectance spectrum, the direct band gap value (2.77 eV) of the material was estimated. The electrochemical characterization of the LiVMoO6 obtained was performed for the first time by assembling an all-solid-state cell, employing LiVMoO6 as a cathode active material. Discharge–charge measurements for 10 cycles were performed in the potential range from 1.8 to 3.7 V under a current density of 0.1 mA cm−2 at room temperature. The assembled all-solid-state Li-In/80Li2S·20P2S5 glass–ceramics/LiVMoO6 battery presents a sustainable reversible capacity of 35 mAh g−1 and a coulombic efficiency close to 100 % after the second to the 10th cycles.

Glass formation ability in three different sections: WO 3 –ZnO–Nd 2 O 3 ; (100-x) (0.8WO 3 ·0.1ZnO·0.1Nd 2 O 3 )·xAl 2 O 3 , x = 5–30 mol% and 90(xWO 3 ·yZnO·zNd 2 O 3 )·10Al 2 O 3 from WO 3 –ZnO-Nd 2 O 3 –Al 2 O 3 system is investigated by melt quenching technique. Glasses are obtained from the compositions with a high WO 3 content (65–75 mol%). According to DTA data the glass transition temperature (T g ) is in the range 508–525 °C and the glass crystallisation temperature (T x ) is around 600 °C. Neodymium tungstates, Al 2 (WO 4 ) 3 , ZnWO 4 and WO 3 are identified in the XRD patterns of quenched samples beyond the glass formation region. The structure of glasses is studied by IR, Raman and DR-UV–Vis spectroscopies. It is established that the amorphous network is built up mainly by WO 6 octahedra, connected by W–O–W bridges. This structure does not satisfy the classical concept for the formation of an amorphous network which is built up by MeO 4 tetrahedra.

Glass crystalline materials from the WO3-ZnO-La2O3-Al2O3 system containing high WO3 concentrations (60–76 mol%) were prepared by controlling the glass crystallization and were then employed as humidity based sensors. According toX-ray analysis, WO3 separates as a crystalline phase from the amorphous structures with the nominal compositions 76WO3·9.5ZnO·9.5La2O3·5Al2O3 and 60WO3·7.5ZnO·7.5La2O3·25Al2O3 after the heat treatment. Samples were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) for elemental analysis. Using the screen printing technique, the synthesized crystalline glass samples were deposited onto interdigidated Pt electrodes; then the sensors were tested in the range from 0.0% to 96% relative humidity (RH) at room temperature. It was observed that the increase in the content of WO3 leads to improve sensor sensitivity towards RH.

The local structure and the connectivity in the amorphous network of glasses from MoO3-Bi2O3 and MoO3-Bi2O3-CuO systems have been studied by comparative analysis of crystalline and amorphous phases using X-ray photoelectron spectroscopy. According to the XPS data the amorphous networks of both glass systems consist mainly of MoO4 tetrahedra as well as of small amounts of MoO6 octahedra. Based on the O1s spectra analysis it was suggested that the MoO6 octahedra are connected by bridging Mo O Mo bonds, while the MoO4 tetrahedra participate in the formation of mixed type Bi O Mo bonds. The presence of mixed Bi O Mo bonds with a relatively significant covalent character is crucial for the glass formation. Mainly Mo6 + and Bi3 + ions were detected in MoO3-Bi2O3 glasses and additionally Cu+ and Cu2 + ions were observed in MoO3-Bi2O3-CuO amorphous samples. UV-visible diffuse reflectance analysis confirmed the XPS data, revealing the presence of Mo6 +, Bi3 + and Cu2 + ions in the glasses. Formation of MoO4 tetrahedral units (absorption band at 260 nm) in the amorphous network was also found by optical absorption spectra. The role of MoO3 as glass former was confirmed.

This paper presents the comparison of nitrogen incorporation in GaAsN and InGaAsN layers grown on GaAs substrate from Ga- and In-rich solution, respectively, by liquid-phase epitaxy. Polycrystalline GaN has been used as a source of nitrogen in two cases. The initial epitaxy temperature has been varied in the temperature range 600-550 °C. Nitrogen content in Ga1-xAsNx grown layers has been determined to be in the range 0.1-0.5%. Higher nitrogen incorporation efficiency has been found for quaternary InGaAsN layers grown under carefully chosen lattice matched conditions. The incorporation of nitrogen into GaAsN and InGaAsN layers has been study by vibrational mode absorption spectroscopy. Nitrogen-induced vibration mode near 472 cm-1 has been registered in GaAsN samples. Preferential In-N bonds and the formation of N-centred In3Ga1 clusters have been identified for lattice matched to GaAs epitaxial InGaAsN layers. Electrical properties of the samples have been characterized by temperature-dependent Hall effect measurements. Nominally undoped GaAsN and InGaAsN grown layers are n-type with Hall concentration about one order of magnitude higher in comparison to layers not containing nitrogen. Thermally activated increase in the free carrier concentration at temperatures higher than 150 K is observed which indicates the presence of N-related deep donor levels below dilute nitride conduction band edge. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Crystallographic and transport properties of nominally undoped and Sn-doped InGaAsN layers grown by low-temperature LPE have been studied and related to the growth conditions. In the case of lattice matching, flat and uniform mirror-like layers of 8–10 μm in thickness are obtained. The compositions of the layers under study have been determined by combination of X-ray microanalysis and X-ray diffraction methods to be In 0.035 Ga 0.065 As 0.086 N 0.014 . The lattice mismatch between layer and substrate Δ a l / a s calculated from X-ray diffraction curves is less than−7×10 −4 for all samples. The layers grown at lower epitaxy temperatures exhibit the highest crystalline quality, better lattice match and better homogeneity. This is in good agreement with the results of morphological study by atomic force microscopy which show root mean-square surface roughness of 0.18 nm for the best layers. CV and Hall measurements reveal that intentionally undoped InGaAsN layers are n-type with free carrier concentration about one order of magnitude higher in comparison to layers not containing nitrogen and high electron mobility values over 2000 cm 2 /Vs. A dramatic reduction in the free carrier concentration and slightly increase in mobility are observed for Sn-doped InGaAsN layers.

The glass formation region in the ternary ZnO―Bi 2 O 3 ―WO 3 system is determined by melt quenching technique (cooling rates 10 1 –10 2 K/s). New original glasses are obtained in a narrow concentration range with high WO 3 content (60–75 mol%). Homogeneous glasses of the composition (100 − x)[0.2ZnO·0.3Bi 2 O 3 ·0.5WO 3 ]xMoO 3 , were obtained between 20 and 60 mol% MoO 3 . Characterization of the amorphous samples was made by x-ray diffraction (XRD), differential thermal analysis (DTA) and infrared spectroscopy (IR). The thermal stability of glasses decreases with the increasing of MoO 3 content. The glass transition temperature, T g , varies between 340–480 °C, while the crystallization temperature, T x , varies between 388–531 °C. The tungstate glasses possess higher crystallization temperature (T x over 500 °C) in comparison with the other vanadate and molybdate non-traditional glasses. The glass network is realized by transformation of three-dimensional structure of WO 3 into a layered one, consisting mainly of WO 6 units. We supposed that the network of quaternary glasses is built up by MoO 4 , MoO 6 and WO 6 . At low concentration ZnO and Bi 2 O 3 facilitate the disorder in the supercooled melts, while at high concentration stimulate crystallization processes. These oxides belong to the intermediate ones.

This work demonstrates the possibility for low-temperature Liquid-Phase Epitaxy (LPE) growth of lattice matched to GaAs substrate dilute nitride InGaAsN layers with good crystalline quality and high Hall electron mobility. X-ray microanalysis and X-ray diffraction methods have been used to determine the composition and crystalline quality of the grown InGaAsN layers. Surface roughness is examined by atomic force microscopy. N-related local vibration modes are observed by Raman scattering. The Hall electron mobility and free carrier concentration have been measured in the temperature range 80-300K by conventional Van der Pauw method.

International audience; The present work demonstrates the possibility to use liquid phase epitaxy to incorporate nitrogen in epitaxial GaAsN/GaAs and GaInAsN/GaAs heterostructures, including nanoscaled ones. The structures are grown from Ga - and GaIn - melts containing polycrystalline GaN as a nitrogen source. The red shift of the absorption spectra corresponds to nitrogen content in the epitaxial layers near or less than 0.2 at %. Photoluminescence spectra of dilute nitride GaAsN and GaInAsN show emission from localized nitrogen states - N-nanoclusters of more than two N atoms. These studies show that the melt grown dilute GaAsN and GaInAsN nanostructures can be used for solar cells with extended long wavelength edge. (C) 2010 Published by Elsevier Ltd

GaSb based III-V heterostuctures are attractive for optoelectronic devices such as midin- frared lasers, detectors, and thermophotovoltaics (TPVs). In this paper the growth and characterization of GaInAsSb and GaAlAsSb quaternary layers, lat-tice-matched to GaSb substrate, are reported, with a particular focus on these alloys for TPV devi-ces. High-quality with a mirror-like surface morphology epilayers Ga1-x InxAsy Sb1-y with In content x in the range 0.1-0.22 and Ga1-xAlxAsySb1-y layers with Al content up to 0.3 in the solid are grown by Liquid-Phase Epitaxy (LPE) from In- and Ga-rich melt, respectively. The compositions of the quaternary compounds are determined by X-ray microanalysis. The crystalline quality of GaInAsSb/ GaSb and GaAlAsSb/GaSb heterostuctures is studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements.

Glasses in the MoO 3 –CuO–PbO system are obtained at high cooling rates (10 4 –10 5 K/s) and characterized using X-ray diffraction (XRD), differential thermal analysis (DTA), infrared (IR) and X-ray photoelectron spectroscopy (XPS). Two glass formation regions are determined: one with compositions having a high MoO 3 content (50–80 mol%) and the other in the PbO-rich compositions (65–80 mol%). In the region of MoO 3 -rich compositions the building units of the amorphous network are МоО 6 , МоО 4 and CuO 4 groups. For these high MoO 3 contents and respectively low PbO concentrations, the lead oxide is supposed to act as a network modifier while at high content PbO is found to be the main glass network former. In latter case the structure of glasses is formed by chains of PbO n ( n = 3, 4) polyhedra, between which there are isolated MoO 4 and CuO 4 complexes. IR and XPS data reveal the existence of Mo–O–Mo, Mo–O–Me(Me’) (where Me = Cu 2+ , Cu 1+ and Me’ = Pb) and Me(Me’)–O–Me(Me’) bonds in the amorphous network. Surprising result is found for low PbO content (10 mol%) where the lead oxide acts as glass network modifier: the actual MoO 3 content drops strongly which is accompanied with a significant increase of the actual CuO content with respect to their nominal MoO 3 –CuO composition. Such effect is not observed in PbO-rich composition (70 mol%) where PbO has a role of network former.

α-Bi2Mo3O12 and β-Bi2Mo2O9 crystal phases have been synthesized by crystallization of a glass for a short time. Amorphous samples with the compositions corresponding to the alpha and beta bismuth molybdates have been obtained at high cooling rates (104-105 K/s). XRD, DTA and SEM studies were performed to examine the phase formation, thermal behavior of the glasses and the microstructure of obtained crystalline products. By scanning electron microscopy it was shown that the obtained bismuth molybdates consist of dense agglomerates, containing uniform distributed crystals with submicron size.

The lithiated transition metal oxide LiVMoO6 has been synthesized by a novel melt quenching method that presents some advantages as compared to the classical solid-state reaction and soft-combustion synthesis. These are: the short preparation time and the possibility to control the grain size of LiVMoO6 powders. The local structure of LiVMoO6 samples prepared in different ways was characterized by IR spectral analysis. The oxidation state of Li, V, and Mo was determined by X-ray photoelectron spectroscopy.

Measurements of Ga–As–Bi liquidus composition at 600 °C for Ga–Bi–GaAs range are reported. High quality GaAs layers and Al 0.28 Ga 0.72 As/GaAs single quantum well (SQW) structures with different well thicknesses are grown from a mixed Ga + Bi solvent by low-temperature liquid-phase epitaxy method. They are characterized by the Hall effect and photoluminescence (PL) measurements. Significant changes in the layer electrical properties are observed with varying the Bi content in the solution. The layers grown from a mixed solution with 20–30% Bi content are n-type with carrier concentration of 10 14 cm − 3 and mobility of 40 000 cm 2 /Vs at 77 K, while p-type high resistivity layers are obtained from a solution with more than 70% Bi content. PL spectra of the SQW structures grown from Ga + 25% Bi solution at 2 K show that the roughness at the interface is less than two monolayers.

We present a study of melt grown dilute nitride InGaAsN layers by x-ray photoelectron spectroscopy (XPS), Raman and photoluminescence (PL) spectroscopy. The purpose of the study is to determine the degree of atomic ordering in the quaternary alloy during the epitaxial growth at near thermodynamic equilibrium conditions and its influence on band gap formation. Despite the low In concentration (~3%) the XPS data show a strong preference toward In–N bonding configuration in the InGaAsN samples. Raman spectra reveal that most of the N atoms are bonded to In instead of Ga atoms and the formation of N-centred In3Ga1 clusters. PL measurements reveal smaller optical band gap bowing as compared to the theoretical predictions for random alloy and localised tail states near the conduction band minimum.

WO3 and WO3-based materials in the form of thin films, either as bulk or as nanostructures, have been widely used for the detection of a variety of gases, such as NO2, H2, NH3 and Cl2. The purpose of this study was to prepare materials from the WO3-ZnO-Nd2O3-Al2O3 system containing high amount of WO3 for applications in environmental monitoring by applying the melt quenching method. Homogenized batches of the starting oxides were melted for 20 min at 1,240 °C in platinum crucibles in air atmosphere. The melts were quenched by pouring and pressing between two copper plates (cooling rates 101–102 K/s). Glassy-crystalline samples containing the monophase AlW12O37.5 was produced by quenching a melt with the composition of 80WO3⋅10Nd2O3⋅10Al2O3. Glassy-crystalline sample containing nanosized W18O49 (~60 nm) was obtained after cooling of a melt with the composition 76WO3⋅9.5ZnO⋅9.5Nd2O3-5Al2O3. A mixture of WO3 and AlW12O37.5 in the amorphous matrix was prepared by crystallization of a quenched sample with the composition 75WO3⋅10Nd2O3⋅5ZnO⋅10Al2O3. Samples were prepared by the screen printing technique as gas sensor s; thereafter dc resistance measurements were performed in the presence of relative humidity and ammonia. It was established that the glassy-crystalline sample containing the monophase AlW12O37.5 exhibits a significant sensitivity towards ammonia and relative humidity, while other phases show a good sensitivity only towards relative humidity.

This paper reports on growth and doping experiment of GaAs and AlGaAs layers fabricated by low-temperature liquid-phase epitaxy (LPE). We demonstrate precise layer composition and thickness controllability for the low-temperature LPE growth. The investigations on the doping of the layers show that the suitable dopants for practical use are Zn, Ge and Mg for p-type, and Sn, Te for n-type doping. We describe the successful growth of Al 0.28 Ga 0.72 As/GaAs single quantum well (SQW) structures, analysed by photoluminescence measurements. Our results indicate that LPE growth in low-temperature variant allows to obtain SQW structures with abrupt well/barrier heterointerfaces and fluctuation in the well thickness within a few monolayers.

This paper describes the spectral characteristics of GaAs solar cells grown by low-temperature liquid phase epitaxy (LPE). It demonstrates improvements in blue response and peak internal quantum efficiencies of 100 percent for an optimized cell structure with isovalent In doped base and ultrathin (

We present an experimental and theoretical study of GaInAs(Sb)N layers with thickness around 2 mu m, grown by liquid-phase epitaxy (LPE) on n-type GaAs substrates. The samples are studied by surface photovoltage (SPV) spectroscopy and by photoluminescence spectroscopy. A theoretical model for the band structure of Sb-containing dilute nitrides is developed within the semi-empirical tight-binding approach in the sp(3)d(5)s*s(N) parameterisation and is used to calculate the electronic structure for different alloy compositions. The SPV spectra measured at room temperature clearly show a red shift of the absorption edge with respect to the absorption of the GaAs substrate. The shifts are in agreement with theoretical calculations results obtained for In, Sb and N concentrations corresponding to the experimentally determined ones. Photoluminescence measurements performed at 300K and 2 K show a smaller red shift of the emission energy with respect to GaAs as compared to the SPV results. The differences are explained by a tail of slow defect states below the conduction band edge, which are probed by SPV, but are less active in the PL experiment. Funding Agencies|research fund of the Sofia University [114/2016]; COST action 1406 MutiscaleSolar

The structure of molybdate glasses have been investigated by neutron and high-energy X-ray diffraction coupled with Reverse Monte Carlo (RMC) simulation technique. From the modelling the partial atomic correlation functions g ij(r), the coordination number distributions CN ij and bond angle distributions have been revealed. For binary 90MoO3-10Nd2O3 glass composition the fraction of MoO4/MoO6 was 0.55/0.25. Three type of ternary system have been studied, where the most important structural units was authenticated. For MoO3-Nd2O3-B2O3 sample mixed MoO4-BO4 and MoO4-BO3 linkages form pronounced intermediate-range order. In case of MoO3-ZnO-B2O3 series the BO3 and BO4 units are linked to MoO4 and/or ZnO4, forming mixed MoO4-BO4(BO3), MoO4-ZnO4 and ZnO4-BO4(BO3) bond-linkages.