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Graphical abstract Imaginary part of the dielectric function of the Ge x Sb 40-x Se 60 films in the middle-IR range (dielectric loss function Im(−1/ ε) in the inset). Highlights • Chalcogenide films from Ge x Sb 40-x Se 60 system were deposited on quartz substrate. • The optical constants are determined in the 0.20–33 μm spectral range by ellipsometry. • The films possess 80% transmission in a wide spectral region of (0.85–3.4) μm. • IRSE studies identified the O- and H-related impurity chemical bonds. • RMC modeling reproduced the Ge Se and Sb Se cell units and cross-linked Ge Ge bonds. • Smooth surfaces with continuous structure of grains are found by AFM. Abstract Thin films of Ge x Sb 40-x Se 60 (x = 15, 20, 25, 27, 32 and 35 at.%) were deposited on quartz by vacuum thermal evaporation of the pre-synthesized parental glasses powders. By spectroscopic ellipsometry the complex refractive index values are determined in the 0.20–33 μm spectral range. The optical band gap and single oscillator energies are established as a function of the Ge content and average coordination number Z. In the (0.85–3.5) μm spectral range the Ge x Sb 40-x Se 60 films possess about 80% transmission. Infrared ellipsometric and Raman studies identified Se Se and Ge Ge homopolar bonds, oxygen and hydrogen related impurity bonds and heteropolar Ge Se and Sb Se chemical bonds. Neutron- and X-ray Diffraction data coupled with Reverse Monte Carlo simulations support the optical results reproducing the Ge Se and Sb Se cell units and cross-linked Ge Ge bonds. Atomic force microscopic imaging confirmed smooth surfaces with low RMS roughness values (<2.3 nm) and continuous structure of grains of (16–22) nm diameters. All the considered material parameters show peculiarities in the compositional dependences around 27 at.% Ge, corresponding to average coordination number Z = 2.67, testifying structural phase transition at high Ge content in the Ge x Sb 40-x Se 60 films. [ABSTRACT FROM AUTHOR]

The changes in the optical, microstructural and electrical properties, following the nitrogen incorporation into indium tin oxide thin films are investigated. The films are formed by r.f. sputtering from an indium-tin-oxide (80% In2O3-20% SnO2) target in a mixture of Ar and N2 plasma (75% N2-25% Ar and 100% N2 respectively) on fused silica glass substrate. The impact of rapid thermal annealing (up to 500 °C, in N2 ambient) on the properties of indium tin oxynitride (ITON) thin films is also reported. The UV-vis-NIR ellipsometry (SE) characterization of ITON films was performed assuming several realistic approaches based on various oscillator models, using a chemical composition gradient depth profiling, in agreement with the X-ray photoelectron spectroscopy measurements. The Hall measurements show that the ITON films prepared by r.f. sputtering in 75% N2 and annealed at 500 °C behave as degenerate semiconductors. X-ray diffraction analysis proved that ITON thin films retain an amorphous structure even after RTA at 500 °C in N2 ambient and atomic force microscopy showed the formation of continuous and smooth ITON thin films, with a morphology consisting in quasispherical nanometric particles. [ABSTRACT FROM AUTHOR]

Highlights: [•] Results on AFM surface imaging of Ge x Sb(As)40−x S50Te10 films are reported. [•] The films are continuous, isotropic, considerably smooth and show fractal behavior. [•] The protruding grains suggest a columnar growth mechanism. [•] The nanoscaled grain size is larger for the films with Ge x As40−x S50Te10 composition. [ABSTRACT FROM AUTHOR]

Abstract: By applying ellipsometry and extending the measurements from visible to mid infrared spectral range we examined the complex dielectric function of thin layers grown into silicon. The layers were synthesized by high-temperature (1050°C) annealing in oxidizing ambient of plasma immersion N+ ion implanted Si substrates. Siglyph name="sbnd" />Nce:glyph name="sbnd" />Si chemical bonds in the silicon oxide network were identified and confirmed by X-ray photoelectron spectroscopy (XPS). Depending on N+ fluence (1016–1018 N+/cm2) and annealing duration (10 and 20min) the grown layers were identified either as silicon oxynitride with considerably low N content or silicon dioxide enriched with nitrogen. [Copyright &y& Elsevier]

Abstract: N-doping is often used to improve the photocatalytic properties of TiO2 films in order to achieve visible light response. In this work, we study the effect of annealing treatment (temperature and atmosphere) on the structural and optical properties of undoped and N-doped TiO2 films by means of X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Rutherford backscattering (RBS), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE) and UV–VIS optical transmission spectroscopy. Porous five-layer TiO2 films were deposited by sol–gel method on quartz substrate and thermally treated in oxygen or NH3 flow at 500 and 600 °C. Significant doping effect was achieved after annealing at 600 °C in NH3 and a shift in optical bandgap value down to visible range (2.69 eV) was observed. [Copyright &y& Elsevier]

Abstract: With a view to analyse multiresidues of pesticides in soil samples, a new ultrasonic solvent extraction (USE) was compared to the European Norm DIN 12393 for foodstuff (extraction with acetone, partitioning with ethylacetate/cyclohexane and clean-up with gel permeation chromatography (GPC)), the QuECheRS method and a pressurised liquid extraction (PLE) method. Pesticides were analysed with both GC-MS and HPLC-MS/MS. The reference materials were the EUROSOIL 7 and its subsoil SO26 as well as a sea sand. All the substances were observed to be linear in the range of 4–800ngg−1 for the European Norm DIN 12393, 7–1400ngg−1 for the USE method and 20–4000ngg−1 for the QueCheRS and the PLE methods. Limits of detection (LOD) and limits of quantification (LOQ) were with HPLC between 0.006 and 0.23ngg−1 and between 0.022 and 0.77ngg−1, respectively, with the exception of diuron (LOD up to 11.8ngg−1; LOQ up to 39.2ngg−1). With GC they ranged from 3.0 to 87.5ngg−1 and from 10 to 292ngg−1, respectively. All substances could be recovered with USE as well as with the QuECheRS method; the European Norm DIN 12393 could not recover carbendazim and metamitron; the PLE carbendazim, metamitron and monolinuron. For the remaining substances, recoveries at a 500ngg−1 fortification level ranged from 10.9 to 96.3% with the USE. In comparison, the QuECheRS method was the most efficient extraction method with recoveries from 27.3 to 120.9%. It was followed by the European Norm DIN 12393 with recoveries between 6.8 and 108.1% and the PLE with recoveries from 12.2 to 153.2%. Recoveries were higher from the EUROSOIL 7 than from the SO 26. The repeatability expressed in term of standard deviation was below 20% for all substances and all materials. [Copyright &y& Elsevier]

Abstract: A comparative study of the sol–gel films prepared in the SiO2–P2O5 system starting with triethylphosphate, triethylphosphite and phosphoric acid as P precursors was performed. The work addresses basic aspects of physics, chemistry, and engineering of oxide films for applications in microelectronics, sensing, nano-photonics, and optoelectronics by establishing the influence of different precursors on the composition, structure and optical properties of the obtained films. The influence of the type of substrate (glass and indium tin oxide coated glass) and of the thermal treatment (200 and 500 °C) on their structure and properties was studied. By spectroscopic ellipsometry, X-Ray photoemission spectroscopy and atomic force microscopy measurements the high vaporization of the phosphorous during the densification of the films by thermal treatment was noticed when P-alkoxides were used. The phosphoric acid that forms chemical bond with silica network during the sol–gel process leads to better incorporation of P in the silica network as compared to the P-alkoxides. [Copyright &y& Elsevier]

We intend to prepare periodic multilayered structures for photonic applications. With this goal we have performed a study of some characteristics of SiO x -P2O5 films deposited by the sol–gel method on glass and ITO (InSnO x )-coated glass. The as prepared films were annealed to different temperatures (150 and 200°C). The chemical composition of the samples was determined by X-ray Photoelectron Spectroscopy (XPS). The XPS results revealed the presence of P in the as-deposited films. The structural an optical properties were examined by Fourier Transform Infrared Spectroscopy (FTIR), Spectroellipsometry (SE) and UV Transmission Spectroscopy. IR spectra of the deposited films attest the interaction of an amorphous SiO2 with the H3PO4 used as a P-precursor. Refractive indices for individual SiO x -P2O5 determined from SE measurements show a densification of the layer structure with the increasing temperature in the thermal treatment. The UV transmission spectra revealed a lower transmission for the sol-gel SiO x -P2O5 films as compared to ITO/glass substrate. AFM images proved the densification of the films with annealing in agreement with the ellipsometric results. [ABSTRACT FROM AUTHOR]

Abstract: Multilayered TiO2(Fe3+, PEG) films were deposited on glass and SiO2/glass substrates by sol–gel dipping method. The influence of Fe3+ and PEG(polyethylene glycol) concentrations, the number of layers, the thermal treatment time and the temperature on the optical and microstructural properties of the TiO2 films were studied. As-deposited TiO2(Fe3+, PEG) films were very porous, but after the thermal treatment at 500°C, the PEG decomposed and burned out to porosity decreasing. Homogeneous nanostructured films were obtained, where the amorphous and the anatase phases coexist. XRD analysis showed that no rutile phase is observed in the films deposited on SiO2/glass as compared with those deposited directly on glass and that the presence of the anatase phase in the films without PEG is more evident in the three-layers film. The XRD intensity of the main peak of anatase from 25° decreases with the increase of PEG concentration. The optical gap of the TiO2(Fe3+, PEG) films is found in 2.52–2.56eV range and does not essentially depend on the PEG content. [Copyright &y& Elsevier]

Abstract: BaTiO3 thin films were deposited on Pt/Ti/SiO2/Si by rf planar-magnetron sputtering. The films thickness increases with the decrease of both deposition pressure and sample-discharge centre distance. The films annealed at 900°C, for 8h, present direct band gap energy ranged between 3.57 and 3.59eV. The dependence of the structure and microstructure (texture, degree of crystallinity), as well as of the optical characteristics on the deposition parameters, was analysed. Using spectroscopic ellipsometry (SE) measurements coupled with the Bruggeman Effective Medium Approximation (B-EMA), the layer structure and the surface roughness, were determined. The root mean square roughness values of the surface layer, estimated by atomic force microscopy (AFM) analyses, are ranged between 10 and 20nm and were in good agreement with SE data. The obtained films have tetragonal unit cell and show densely packed, non-columnar morphology and hexagon-like crystallite shape. [Copyright &y& Elsevier]

Abstract: InGaN layers were grown by molecular beam epitaxy (MBE) either directly on (0001) sapphire substrates or on GaN-template layers deposited by metal-organic vapor-phase epitaxy (MOVPE). We combined spectroscopic ellipsometry (SE), Raman spectroscopy (RS), photoluminescence (PL) and atomic force microscopy (AFM) measurements to investigate optical properties, microstructure, vibrational and mechanical properties of the InGaN/GaN/sapphire layers. The analysis of SE data was done using a parametric dielectric function model, established by in situ and ex situ measurements. A dielectric function database, optical band gap, the microstructure and the alloy composition of the layers were derived. The variation of the InGaN band gap with the In content (x) in the 0< x ≤0.14 range was found to follow the linear law E g =3.44–4.5x. The purity and the stability of the GaN and InGaN crystalline phase were investigated by RS. [Copyright &y& Elsevier]

Tin-doped indium oxide (ITO) thin films have been deposited by sol–gel process using ‘sols’ of indium and tin isopropoxides. The thickness of one deposited ITO layer is approximately 50 nm. The desired thickness was obtained by 1–5 successive depositions. The XTEM cross-sectional view of an ITO sample with five depositions showed a clear delimitation of the layers with an alternating structure dense/porous ITO layers. The void fraction in porous regions varies between 20 and 25%. Cubic bixbyite In2O3 nanocrystals with size of 10–20 nm and no phases separation of tin oxide were observed. The optical properties of the films have been investigated by optical transmission and spectroscopic ellipsometry. Reliable optical constants and porosity are obtained only with the model of internal structure based on XTEM results. [Copyright &y& Elsevier]

TiO2 based nanustructured coatings have been prepared by sol–gel method on glass and SiO2/glass substrates. The films were thermally treated in oxidative and reductive conditions at 500 °C. The influence of the substrate and of the thermal treatment on the optical properties of the films was studied. The samples were characterized by spectroscopic ellipsometry (SE), scanning electron microscopy (SEM), Rutherford backscattering spectroscopy (RBS) and Raman spectroscopy. SE results supported by other optical and structural measurements have proven the transformation of CuO from as-prepared samples into Cu2O in samples heated in oxidative conditions and into metallic Cu in samples heated in reductive conditions as well as the transformation of the amorphous TiO2 in anatase. [Copyright &y& Elsevier]

In this paper we study the changes in the microstructural and optical properties of silicon thin films produced by the variation of the parameters (temperature and pressure) of the low-pressure chemical vapour deposition (LPCVD) process. Silicon thin films prepared by LPCVD on oxidized silicon substrates over a large range of process parameters (Tdep=500–615°C, pdep=20–100 Pa) have been characterized by Raman spectroscopy, spectroscopic ellipsometry (SE), X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques. The phase transition of as-deposited silicon from an amorphous to a crystalline phase via an intermediate mixed phase (few grains in amorphous silicon matrix) can be monitored by the changes in the optical properties and in the Raman spectra. LPCVD parameters, which control the deposition kinetics, are able to influence the optical properties, the structure and/or morphology of the as-deposited LPCVD silicon films. The SE and Raman results prove that it is possible to grow by LPCVD (from pure silane), a silicon film in a (poly)crystalline state at a temperature as low as 500°C. [Copyright &y& Elsevier]

Structures containing silicon nanocrystals (nc-Si) are very promising for Si-based light-emitting devices. Using a technology compatible with that of silicon, a broader wavelength range of the emitted photoluminescence (PL) was obtained with nc-Si/SiO2 multilayer structures. The main characteristic of these structures is that both layers are light emitters. In this study we report results on a series of nc-Si/SiO2 multilayer periods deposited on 200 nm thermal oxide SiO2/Si substrate. Each period contains around 10 nm silicon thin films obtained by low-pressure chemical vapour deposition at T=625°C and 100 nm SiO2 obtained by atmospheric pressure chemical vapour deposition T=400°C. Optical and microstructural properties of the multilayer structures have been studied by spectroscopic ellipsometry (using the Bruggemann effective medium approximation model for multilayer and multicomponent films), FTIR and UV–visible reflectance spectroscopy. IR spectroscopy revealed the presence of SiOx structural entities in each nc-Si/SiO2 interface. Investigation of the PL spectra (using continuous wave-CW 325 nm and pulsed 266 nm laser excitation) has shown several peaks at 1.7, 2, 2.3, 2.7, 3.2 and 3.7 eV, associated with the PL centres in SiO2, nc-Si and Si–SiO2 interface. Their contribution to the PL spectra depends on the number of layers in the stack. [Copyright &y& Elsevier]

Inorganic–organic hybrid materials can offer multifunctionality and allow properties tailoring from subnanometer (atomic) to submillimeter (mesoscopic) length scales. That is why these films could play a significant role in the field of micro- and nano-photonic devices (waveguids, emitting devices, quantum dot devices, photonic band gaps and holographic materials).The organic groups can modify the inorganic backbone by reducing the connectivity of the gel network allowing thick film deposition and lessening the processing temperature. In order to follow the sol–gel chemistry in the case of the substituted alkoxides that influence the molecular species presented in solution at the moment of deposition, model systems based on tetraethoxysilane (TEOS), methyltriethoxysilane (MTEOS) and vinyltriethoxysilane (VTEOS) were investigated. The hybrid organic–inorganic sol–gel-based photonic components were realized with phenyltriethoxysilane (PTEOS).The composition and the process were optimized to allow a better control of the optical parameters (losses, refractive index, transmission), to reduce the processing temperature and to improve photosensitivity. [Copyright &y& Elsevier]

The structural and morphological properties of low temperature annealed (600 °C, for 26 h) LPCVD silicon layers prepared from pure silane in a large range of deposition temperatures (500–615 °C) and pressures (20–100 Pa) have been investigated in order to see the changes appearing in the LPCVD Si film with respect to the as-deposited films. The physical characterization of as-deposited and annealed films has been performed by X-ray diffraction (XRD), spectroellipsometry (SE) and atomic force microscopy (AFM) techniques. Surface roughness information extracted from AFM and SE showed good agreement and revealed the annealing effect on LPCVD Si films as a function of CVD condition. The crystalline phase evolution in LPCVD Si films at different annealing temperatures was studied by XRD and SE techniques. A high degree of crystallization was obtained in all silicon films. Two models, Tauc and Cody (applied to the ellipsometric spectra), were used to estimate the evolution of the optical band gap with the annealing. The results show a strong link between annealing and deposition temperatures on the one hand and the physical and optical properties of polysilicon films on the other hand. [Copyright &y& Elsevier]

Presents a study which investigated the voltage and current controlled bistability of segmented anode lateral insulated gate bipolar transistors. Device structure and characteristics; Numerical simulations and discussion; Conclusions.

We report on a combined theoretical and experimental determination of the Fermi level position in wurtzite Ga1–xMnxN films with x = 4% and x = 10% as grown by molecular beam epitaxy. By means of ellipsometric measurements, the real part of the frequency-dependent conductivity is determined. An electronic model in the framework of the effective bond-orbital model is parameterized in order to theoretically reproduce the measured transport properties. Predictions for the long-wavelength behaviour as a function of the Fermi level are made. The corresponding density of states obtained in this model is in qualitative agreement with first-principle calculations. The absence of a significant experimental peak in the AC conductivity for small frequencies indicates that the Fermi level lies in a gap between two Mn-related impurity bands in the host band gap. [ABSTRACT FROM AUTHOR]

Abstract: High spectral (1.5 cm−1) and spatial (~1000 nm lateral and vertical) resolution Raman spectra taken at room temperature in the depth of a thin (350 nm) YBCO film with good superconducting properties are presented and discussed. The differences between Raman spectra corresponding to different depths in the film are interpreted as depth-dependant changes in the film''s structure, degree of oxygenation, and superconducting properties. These changes are in agreement to what we expect from a film obtained by pulsed laser deposition technique. The resonance of the most significant Raman shift (500 cm− 1), monitoring the oxygen content of YBCO films, for 488 nm excitation light, was used to overcome the relatively small penetration depth of visible light in YBCO (~200 nm). We found the range of parameters for the depth profiling Raman system such as to obtain the maximum signal intensity and a reasonable number of distinctive Raman spectra corresponding to different depths of the YBCO film. [Copyright &y& Elsevier]

Abstract: Pesticides in foodstuff are becoming a major issue due to their intensive use in agriculture. Thus an appropriate control of their residues in food samples has to be operated. In this study we analysed 105 pesticides with GC/SQ-MS and 46 pesticides with HPLC/IT-MS after extraction with the QuECheRS method in four matrices (grape, lemon, onion and tomatoes). For GC-amenable substances, the LOD and LOQ ranged from 0.4 to 48.2μg/kg and from 1.2 to161μg/kg, respectively. For HPLC-amenable substances, they varied from 1.0 to 115μg/kg and from 3.3 to 382μg/kg, respectively. With GC/MS, 61–82% of the substances showed a recovery in the range of 70–110% and 6–30 % presented a recovery higher than 110% at the 500μg/kg fortification level. With HPLC/MS, 87–93% of the substances presented recoveries in the range of 70–110% at the 500μg/kg fortification level compared to 78–85% at the 50μg/kg fortification level. Lemon and onion showed poor recoveries but are known to be difficult matrices (high acidic and high sulfur content, respectively). The method was proved to be repeatable with RSD lower than 20% at 500μg/kg and lower than 15% at 50μg/kg with both devices. [Copyright &y& Elsevier]

Abstract: This work describes the preparation of HfO2 thin films by the sol–gel method, starting with different precursors such as hafnium ethoxide, hafnium 2,4-pentadionate and hafnium chloride. From the solution prepared as mentioned above, thin films on silicon wafer substrates have been realized by ‘dip-coating’ with a pulling out speed of 5cmmin−1. The films densification was achieved by thermal treatment for 10min at 100°C and 30min at 450°C or 600°C, with a heating rate of 1°Cmin−1. The structural and optical properties of the films are determined employing spectroellipsometric (SE) measurements in the visible range (0.4–0.7μm), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The main objective of this paper was to establish a correlation between the method of preparation (precursor, annealing temperature) and the properties of the obtained films. The samples prepared from pentadionate and ethoxide precursors are homogenous and uniform in thickness. The samples prepared starting from chloride precursor are thicker and proved to be less uniform in thickness. Higher non-uniformity develops in multi-deposition films or in crystallized films. A nano-porosity is present in the quasi-amorphous films as well in the crystallized one. For the samples deposited on silicon wafer, the thermal treatment induced the formation of a SiO2 layer at the coating–substrate interface. [Copyright &y& Elsevier]

Abstract: Multiferoic materials (having coupled electric, magnetic and structural order parameters that result in simultaneous ferroelectricity, ferromagnetism, and ferroelasticity) present opportunities for potential application in information storage, the emerging field of spinotronics and sensors. The perovskite BiFeO3 is ferroelectric [Curie temperature (T c) ∼1103K] and antiferromagnetic [Neél temperature (T N) ∼643K], exhibiting weak magnetism at room temperature. Conditions for synthesizing single BiFeO3 phase are critical since the temperature stability range of the phase is very narrow. Moreover, it is also difficult to control oxygen stoichiometry in the sample. In this work the preparation of BiFeO3 thin films by a specific wet chemical route is discussed. Respective influence of the precursors, thermal annealing condition, the substrate and, generally speaking, the preparation process of the films is presented. Results obtained by X-ray diffraction and spectroscopic elipsometer (SE) was used to characterize the obtained films. [Copyright &y& Elsevier]

Abstract: We report spectroscopic characterization of epitaxial YBCO thin films grown on LaAlO3 by pulsed laser deposition. Raman spectroscopy and spectroscopic ellipsometry were used for film characterization and the results were correlated with X-ray diffraction measurements. The mentioned techniques allowed us to analyze crystallographic, micro-structural, and morphological properties of YBCO thin films. We also demonstrated that relatively low resolution Raman spectroscopy and spectroscopic ellipsometry are reliable techniques for a rapid and non-destructive characterization of epitaxial YBCO thin films. [Copyright &y& Elsevier]

Al1-xInxN layers with an indium content between x=10.5% and x=24% were grown by metal-organic vapor-phase epitaxy and characterized concerning their optical, structural and morphological properties with regard to the realization of optoelectronic devices. The indium content and the strain of these layers were measured by high resolution x-ray diffraction. Ellipsometric measurements were used to determine the optical constants [refractive index n(λ) and extinction coefficient κ(λ)] in dependence of wavelength and indium content. The values determined for the electronic bandgaps are in good agreement with theoretical predictions and previous publications on this topic but are more focused on AlInN layers which are pseudomorphically grown on GaN. A bowing parameter of b=10.3±0.1 was determined for fully strained layers with an indium content between 13% and 24%. In order to investigate the suitability of these layers for use in distributed Bragg reflectors, the surface morphology is characterized with respect to the indium content. Furthermore, the influence of an annealing step which often is necessary during device growth, was studied. The influence of this annealing step on the roughness was analyzed by atomic force microscopy, while structural features are monitored by high resolution secondary electron microscopy images. Based on these results distributed Bragg reflectors for the green spectral region with up to 40 pairs and a peak reflectivity of 97% have been realized. Transmission electron microscopic analysis of the layer interfaces are in good agreement with the atomic force and secondary electron microscopy images of the single layer surfaces. [ABSTRACT FROM AUTHOR]

Aluminium nitride (AlN) films were synthesized by pulsed laser ablation of poly-AlN target on Si(100) substrates using a KrF* excimer laser source ( λ = 248 nm, τ ≤ 25 ns), with incidence laser fluence of ~ 3 J/cm and laser pulse repetition frequencies (LPF) of 3, 10 and 40 Hz, respectively. The depositions were performed in nitrogen pressure of 0.1 Pa and at substrate temperatures of 450 and 800 °C. The AlN structures were studied by transmission electron microscopy, atomic force microscopy (AFM), Fourier transform infrared reflectance (FTIR) spectroscopy and spectroscopic ellipsometry (SE) measurements. The results show that at 450 °C and LPF of 3 Hz the AlN film is entirely amorphous, while at LPF of 10 and 40 Hz nanocrystallites with h-AlN phase appear in the grown films. At 800 °C, well-textured h-AlN nanocrystallites with columnar grains are formed. Growth of nanocrystallites in the 450 °C AlN films, similar to films grown at 800 °C, is possible when the films are deposited onto a high-temperature AlN 'seed' layer, as they follow the columnar structure but with small-sized crystallites and a weaker texturing. AFM imaging reveals increasing surface roughness with the degree of crystallinity in the synthesized films. The structural changes are well correlated with the variation in the optical parameters registered by FTIR and SE. [ABSTRACT FROM AUTHOR]

Titania films doped with low amount of vanadium were deposited on different substrates (microscope glass, microscope glass covered with SiO 2 barrier layer, and silicon wafer with a thermally grown layer of SiO 2 ) by dip coating from solutions prepared by sol-gel and microwave (MW) assisted sol-gel syntheses. The selected molar composition was 99.95:0.05 which corresponds to 0.03 at% of V. The films were characterized by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray diffraction (XRD) and Spectroscopic Ellipsometry (SE). The deposited films thermally treated at 450 °C, presented homogeneous and continuous nanostructured surfaces and good adherence to the substrates used. All samples crystallized in anatase phase and have good optical properties. The highest transmission value was obtained for the V-doped TiO 2 films (T > 90%) deposited from solutions prepared by microwaves assisted sol-gel method. Based on the obtained results it was concluded that the method of preparation has higher influence on the properties of the resulted films than the substrates used. [ABSTRACT FROM AUTHOR]

Aluminum Nitride (AlN) thin films were synthesized on Si (100) wafers at 450 °C by pulsed laser deposition. A polycrystalline AlN target was multipulsed irradiated in a nitrogen ambient, at different laser pulse repetition rate. Grazing Incidence X-Ray Diffraction and Atomic Force Microscopy analyses evidenced nanocrystallites with a hexagonal lattice in the amorphous AlN matrix. The thickness and optical constants of the layers were determined by infrared spectroscopic ellipsometry. The optical properties were studied by Fourier Transform Infrared reflectance spectroscopy in polarised oblique incidence radiation. Berreman effect was observed around the longitudinal phonon modes of the crystalline AlN component. Angular dependence of the A 1 LO mode frequency was analysed and connected to the orientation of the particles’ optical axis to the substrate surface normal. The role of the laser pulse frequency on the layers’ properties is discussed on this basis. [ABSTRACT FROM AUTHOR]

Mesoporous Zn and Pr modified SnO 2 -TiO 2 mixed powders (Sn:Ti:Zn:Pr contents 60:20:15:5) have been prepared by a modified sol–gel method involving Tripropylamine (TPA) as chelating agent, TritonX100 as template and Polyvinylpyrrolidone as dispersant and stabilizer, respectively. The obtained gels have been dried at different temperatures and calcined in air at 600 and 800 °C, respectively. Phase identification of the synthesized samples and their evolution with the calcination temperature has been performed by X-ray diffraction. N 2 adsorption/desorption isotherms were found to be characteristic for mesoporous materials, showing relatively low values for the specific surface area (15–32 m 2 g −1 ) and nanometric sized pores. In case of the sample calcined at 800 °C, a bimodal pore size distribution can be observed, with maxima at 20 and 60 nm. SEM results demonstrate a porous nanocrystalline morphology stable up to 800 °C. The surface chemistry investigated by XPS reveals the presence of the elements on the surface as well as the oxidation states for the detected elements. At 800 °C a diffusion process of Sn from surface to the subsurface/bulk region accompanied by a segregation of Ti and Zn to the surface is noticed, while Pr content is unchanged. The sensing properties of the prepared powders for CO detection have been tested in the range of 250–2000 ppm and working temperatures of 227–477 °C. [ABSTRACT FROM AUTHOR]

We report on multi-stage pulsed laser deposition of aluminum nitride (AlN) on Si (1 0 0) wafers, at different temperatures. The first stage of deposition was carried out at 800 °C, the optimum temperature for AlN crystallization. In the second stage, the deposition was conducted at lower temperatures (room temperature, 350 °C or 450 °C), in ambient Nitrogen, at 0.1 Pa. The synthesized structures were analyzed by grazing incidence X-ray diffraction (GIXRD), transmission electron microscopy (TEM), atomic force microscopy and spectroscopic ellipsometry (SE). GIXRD measurements indicated that the two-stage deposited AlN samples exhibited a randomly oriented wurtzite structure with nanosized crystallites. The peaks were shifted to larger angles, indicative for smaller inter-planar distances. Remarkably, TEM images demonstrated that the high-temperature AlN “seed” layers (800 °C) promoted the growth of poly-crystalline AlN structures at lower deposition temperatures. When increasing the deposition temperature, the surface roughness of the samples exhibited values in the range of 0.4–2.3 nm. SE analyses showed structures which yield band gap values within the range of 4.0–5.7 eV. A correlation between the results of single- and multi-stage AlN depositions was observed. [ABSTRACT FROM AUTHOR]

Quasi-amorphous titanium oxynitride (TiON) films were obtained by annealing sol–gel anatase TiO 2 films in NH 3 atmosphere at 600 °C. These films were irradiated with 50 laser pulses using the fourth harmonic (266 nm) radiation of the Nd-YAG laser, with an average fluence of 20 mJ/cm 2 . HRTEM observations of the pulsed laser irradiated films evidenced the rutile TiO 2 nanocrystallites formation. The rutile structure was not present either in the TiON films before the laser irradiation, or in the initial sol–gel anatase TiO 2 films. During the laser irradiation, the film structure remains in the solid state phase, as it results from the temperature estimation and microscopic observations. For the rutile nanocrystals formation, the atomic diffusion length of the oxygen and titanium atoms should be in the nanometric range during the laser pulse action, which implies a diffusivity close to the values observed in the liquid phase. We consider that the rutile phase formation is a proof of the fast atomic diffusion in the solid amorphous matrix, during the laser irradiation. [ABSTRACT FROM AUTHOR]

Nb doped titania (TiO 2 :Nb) multilayered films (1–10 layers) with anatase structure were obtained by the low-cost sol–gel and dipping method on microscope glass substrates, followed by thermal treatment at 450 °C for 1 h. After each layer deposition, an intermediate annealing step was performed at 300 °C for 30 min. Doping TiO 2 sol–gel films with a low amount of Nb (0.8 at%) allows obtaining an improved CO sensor able to operate under environmental atmosphere (air). It was found that the sensor sensitivity is less dependent on the film thickness but is significantly influenced by Nb doping at the optimal working temperature of 400 °C. Good recovery characteristics were obtained for a wide CO detection range, between 0 and 2000 ppm. The gas-sensing behavior of the films was correlated with the structural, chemical and morphological properties of the multi-layered structures. [ABSTRACT FROM AUTHOR]

Тhin films of 5 and 10-layered sol–gel TiO 2 were doped with 1.2 at.% Nb and their structural, optical and electrical properties were investigated. The films crystallized only in anatase phase, as evidenced by X-ray diffraction and selected area electron diffraction analyses. High resolution transmission electron microscopy revealed nanosized crystallites with amorphous boundaries. Current-voltage measurements on metal-TiO 2 –Si structures showed the formation of n + –n heterojunction at the TiO 2 –Si interface with a rectification ratio of 10 4 . The effective donor density varies between 10 16 and 10 17 cm −3 , depending on film thickness. The sheet energy densities under forward and reverse bias are in the order of 10 12 and 10 10 cm −2 eV −1 , respectively. These values and the high specific resistivity (10 4 Ω cm) support the existence of compensating acceptor levels in these films. It was established that the conduction mechanism is based on space charge limited current via deep levels with different energy positions in the band gap. [ABSTRACT FROM AUTHOR]

By codoping with a donor–acceptor pair through a two-step chemical method we have succeed to obtain p-type ZnO thin films on glass. Firstly, a thin undoped ZnO seed layer was deposited by sol–gel method followed by the deposition of In–N codoped ZnO film obtained through the hydrothermal technique. The influence of post-deposition annealing temperature (100 °C, 300 °C and 500 °C) on the samples was investigated from a structural, chemical, morphological and optoelectrical point of view. X-ray diffractometry (XRD), infrared ellipsometry and X-ray photoelectron spectroscopy (XPS) analyses have confirmed the codoped nature of the ZnO thin films. The XRD pattern analysis has established the films have wurtzite nanocrystalline structure, the crystallite sizes varying between 10 nm and 13 nm with the annealing temperature. Continuous and homogenous films with nanorods surface morphology has been obtained, as visualized by scanning electron microscopy measurements. Hall Effect measurements have established that all samples, regardless of annealing temperature, showed p-type conduction due to the successful incorporation of nitrogen in the film, with the highest carrier concentration registered at 500 °C. This is in good correlation with the nitrogen content in the films as revealed from XPS. In all samples, the XPS depth profiling has shown a nitrogen gradient with higher elemental concentration at the surface. [ABSTRACT FROM AUTHOR]

The transparent conductive oxide films with controlled type of conduction are of great importance and their preparation is intensively studied. In our work, the preparation of such films based on doped ZnO was realized in order to achieve controlled type of conduction and high concentration of the charge carriers. Sol–gel method was used for films preparation and several dopants were tested (Sn, Li, Ni). Multilayer deposition was performed on several substrates: SiO 2 /Si wafers, silica-soda-lime and/or silica glasses. The structural and morphological characterization of the obtained films were done by scanning electron microscopy, X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy and atomic force microscopy respectively, while spectroscopic ellipsometry and transmittance measurements were done for determination of optical properties. The selected samples with the best structural, morphological and optical properties were subjected to electrical measurement (Hall and Seebeck effect). In all studied cases, samples with good adherence and homogeneous morphology as well as monophasic wurtzite type structure were obtained. The optical constants (refractive index and extinction coefficient) were calculated from spectroscopic ellipsometry data using Cauchy model. Films with n- or p-type conduction were obtained depending on the composition, number of deposition and thermal treatment temperature. [ABSTRACT FROM AUTHOR]

Nanosized TiO2 layers containing polyethylene glycol (PEG) with 20,000 molecular weight were prepared by sol-gel method and deposited on three different substrates: microscope standard slides, Fluorine doped Tin Oxide (FTO) glass and Silicon, followed by thermal treatment at 450 °C. The effects of the substrate on the microstructural, morphological, chemical and optical properties of the films have been studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), Atomic Force Microscopy (AFM), X-ray Photo-electron Spectroscopy (XPS) and Spectroscopic Ellipsometry (SE). The XRD showed that the film crystallization depends very much on the substrate used, thus the films deposited on glass are amorphous even after 1 h thermal treatment at 450 °C, while the films deposited on Silicon and FTO substrates are crystallized in anatase phase, in good agreement with the TEM analysis. The XPS analysis showed that a rather high carbon relative concentration in the TiO2 film (without PEG) exists; this suggests that an unavoidable carbon contamination occurs and is not related on the presence or absence of PEG. The thickness and surface roughness of the films are clearly dependent on the substrate type. The flat surfaces of glass and Si lead to the formation of thinner TiO2 films (around 30 nm thicknesses), while the FTO substrate surface leads to thicker film (thickness ~100 nm). The porosity of TiO2 films as found by SEM and TEM analyzes is dependent of substrate type; small pore sizes up to 20 nm are characteristic for the films deposited on glass, while larger pore sizes up to 200 nm are found for the films deposited on FTO substrate. Not least, the film transmissions in the visible region are also substrate dependent and the highest values (80%) were obtained for the films deposited on glass. [ABSTRACT FROM AUTHOR]

Abstract: Titanium dioxide thin films with coloured reflections were deposited on glass substrate by robotic spray pyrolysis deposition using titanium (IV) isopropoxide as a precursor and air as a carrier gas. The films' optical properties were analyzed by UV–vis–NIR spectrometry using a 150mm integrating sphere and spectroscopic ellipsometry (SE). The surface properties were evaluated by atomic force microscopy (roughness and morphology) and contact angle measurement (wettability). The colour variation of the films was determined in the CIE (Commission Internationale d'Eclairage) L⁎a⁎b⁎ colour system by using the total reflectance spectra measured in the visible range. Thin films with low roughness (<4.5nm), high transparency (>70%) in the UV–vis–NIR region and hydrophilic properties were obtained. The optical properties, particularly transmittance are not influenced by humidity exposure. The colour of the films depends on the number of deposition sequences due to thickness and surface topology modification. By varying the deposition sequences brownish, purple, light-violet or purple–brown coloured reflections can be obtained. These coloured TiO2 thin films will be used in solar collectors' glazing, supporting increased architectural acceptance. [Copyright &y& Elsevier]

Abstract: Multilayered titania (TiO2) films have been prepared via sol–gel dip-coating method from a tetraethyl-orthotitanate solution that contains 2g of polyethylene glycol (PEG) with different molecular weight (6000, 20,000 and 35,000). The films were deposited on fluorine doped tin oxide (FTO) coated glass and annealed by a thermal treatment at 450°C for 30min. We demonstrated how the structure, the morphology and the optical properties of the films can be controlled by varying the PEG molecular weight and number of depositions. The correlation between these parameters and the film properties was investigated. Sol–gel deposited and PEG doped TiO2 films demonstrate better properties for their use in solar cell applications, by enhancing the transmittance value in the 380–540nm range. [Copyright &y& Elsevier]

Abstract: We report the influence of the normal thermal treatment (TT) and of rapid thermal annealing (RTA) on the microstructural, optical and electrical properties of indium tin oxide (ITO) and nitrogen doped indium tin oxide (ITO:N) thin films. The TT was carried out for 1h at 400°C and the RTA for 1min up to 400°C, both in N2 atmosphere. The ITO and ITO:N films were deposited by reactive sputtering in Argon, and respectively Nitrogen plasma, on Si with (100) and (111) orientation. The present study brings data about the microstructural and optical properties of ITO thin films with thicknesses around 300–400nm. Atomic Force Microscopy analysis showed the formation of continuous and homogeneous films, fully covered by quasi-spherical shaped particles, with higher roughness values on Si(100) as compared to Si(111). Spectroscopic ellipsometry allowed the determination of film thickness, optical band gap as well as of the dispersion curves of n and k optical constants. X-ray diffraction analysis revealed the presence of diffraction peaks corresponding to the same nominal bulk composition of ITO, but with different intensities and preferential orientation depending on the substrate, atmosphere of deposition and type of thermal treatment. [Copyright &y& Elsevier]

Intravenous administration of heparin and heparin-bonded extracorporeal circuits are frequently used to mitigate the deleterious effects of blood contact with synthetic materials. The work described here utilized human blood in a micro-perfusion circuit to experimentally examine the effects of intravenous and surface-bound heparin on cellular activation. Activation markers of coagulation and of the inflammatory response were examined using flow cytometry; specifically, markers of platelet, monocyte, polymorphonuclear leukocyte (PMN), and lymphocyte activation were quantified. The results indicate that surface-bound heparin reduces the inflammatory response whereas systemically administered heparin does not. This finding has important implications for blood-contacting devices, particularly within the context of recently elucidated connections between inflammation pathways and coagulation disorders. Data presented indicate that surface-bound heparin and intravenously administered heparin play distinct, but vital roles in rendering biomaterial surfaces compatible with blood. [ABSTRACT FROM PUBLISHER]

Abstract: N-doped ZnO (ZnO:N) thin films, intended to be used as one of the layers in solar cell applications were deposited by r.f. sputtering, using ZnN target (99.9% purity), on silicon and fused silica substrates. In the gas flow composition, Ar was kept constant (50%) and the O2/N2 ratio was varied as: 40%/10%, 25%/25% and 10%/40%. After deposition, rapid thermal annealing (RTA) at 400 and 550°C for 1min in N2 ambient has been performed. The RTA impact on the optical and microstructural properties of ZnO:N thin films have been investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDX), UV–vis–NIR spectroscopy, UV–vis–NIR spectroscopic ellipsometry (SE) and infrared ellipsometry (IR-SE). The as-deposited (ad) ZnO:N films are polycrystalline with preferentially oriented columnar crystals. After RTA we found ZnO:N films with improved crystallinity and fewer boundary defects. We report optical constants of ZnO:N from UV to IR spectral range as well as the infrared active phononic modes. [Copyright &y& Elsevier]

Abstract: Multifunctional nanomaterials with one-dimensional structure have become very attractive because of their potential applications in biochemistry (bioseparation and biointeraction), drug delivery, catalysis, nanotechnology (optical sensors). In this work we report on the synthesis of SiO2 nanospheres and tubes, in a solution of tartaric acid (TTA), pure water and absolute ethanol, starting with tetraethyl orthosilicate (TEOS) via the addition of ammonium hydroxide. In order to characterize the obtained material, transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), thermogravimetric and thermodifferential analysis (DTA/TGA), FT-IR spectroscopy and spectroellipsometry (SE) were used. The tubes have an outer diameter of 0.1–0.2μm and length of some microns containing also spherical nanoparticles. The dimensions of the obtained nanotubes are tunable, their diameter and length depending on the synthesis conditions. In the presence of meso-tartaric acid no hollow tubes but nanospheres are obtained. The SiO2 tubes and nanospheres have similar structure but very different morphologies. The large surface area and the distinctive inner and outer surfaces represent a great advantage of the nanotubes over conventional nanoparticles, making these materials suitable for doping and differential functionalization. [ABSTRACT FROM AUTHOR]

Abstract: Multilayered TiO2 films were obtained by sol–gel and dipping deposition on quartz substrate followed by thermal treatment under NH3 atmosphere. In an attempt to understand the close relationship between microstructural characteristics and the synthesis parameters, a systematic research of the structure and the morphology of NH3 modified TiO2 sol–gel films by XRD and Atomic Force Microscopy is reported. The surface morphology has been evaluated in terms of grains size, fractal dimension and surface roughness. For each surface, it was found a self-similar behavior (with mean fractal dimension in the range of 2.67–3.00) related to an optimum morphology favorable to maintain a nano-size distribution of the grains. The root mean square (RMS) roughness of the samples was found to be in the range of 0.72–6.02 nm. [Copyright &y& Elsevier]

Abstract: Hydroxyapatite (HA) biocoatings were obtained using two different deposition methods: sol–gel and sputtering. A direct comparison of films obtained using different techniques is necessary because of possible formation of multi-phases and components in HA films. HA films were investigated using spectroscopic ellipsometry (SE) as a powerful method to evaluate composition and structural properties of the films. For both types of films, sputtering and sol–gel, a weak dispersion of the refractive index within the wavelength range 0.4–0.7 µm was found. This corresponds to a high energy bandgap and a high optical transparency in the UV–VIS range. The internal porosity varying in a wide range in the sol–gel films was evaluated using a modeling of SE data. Additionally to SE studies, structural, chemical and optical characterizations of the films were performed using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Two absorption bands observed in the wavelength ranges 550–600 cm− 1 and 1000–1200 cm− 1 can be attributed to the major absorption modes associated with HA in agreement with published data. From XPS analysis, the atom ratio Ca/P was found for sol–gel films close to the stoichiometric value 1.67. For sputtering films, a higher Ca/P ratio of about 2.1 was estimated. However, similar FTIR spectra have been recorded for both sputtering and sol–gel films. XRD studies show also similar crystallization conditions by annealing at temperatures higher than 500 °C. [Copyright &y& Elsevier]

Samples of vegetables and cereals from Egypt were screened for 113 pesticides, of which 68 were quantified, using gas chromatography-mass spectrometry (GC/MS) with limits of detection (LODs) ranging from 0.02 to 1.9 µg kg-1. In addition, the residues of 17 non-dioxin-like polychlorinated biphenyls (NDL-PCBs) were measured in samples of animal origin (meat, dairy products and seafood) using high-resolution gas chromatography (HRGC)/high-resolution mass spectroscopy (HRMS). None of the cereal samples and 72.7% of the vegetables contained any detectable levels of the pesticides. Detectable residues, not exceeding the current European Union maximum residue limits (MRLs) were found in 27.3% of vegetables. The estimated daily intake for detected pesticides was well below their corresponding acceptable daily intake (ADI), with exposure ranges between 0.002% of the ADI for profenofos and 0.2% of the ADI for lambda-cyhalothrin. The sum concentration of 17 PCBs congeners varied between 2.5 and 322 ng g-1 fat, corresponding to 1.7-216 ng g-1 fat for the seven indicator PCBs. The highest values were measured in seafood, the lowest in dairy products. Hexa-CB 153, 138 and hepta-CB180 were the congeners with the highest contribution. PCBs congener profiles found in most of the samples were consistent with the expected profile for Aroclor 1260 and 1262. PCBs' contamination levels reported in this paper were many times lower than in developed countries, except for chicken samples. Also, the dietary intake of seven indicator PCBs due to the consumption of food of animal origin (4.84 ng kg-1 body weight day-1) from Ismailia city, Egypt, is several times lower than the intake in European Union countries. [ABSTRACT FROM AUTHOR]

Abstract: One of the most interesting category of multifunctional systems is the magnetoelectrics (ME), i.e., materials having simultaneous magnetic and ferroelectric activity. The present paper describes a simple low-temperature synthesis method of preparing bismuth ferrite thin films by a wet chemical route, using bismuth and iron nitrates and two chelating agents (citric acid and polyvinyl alcohol). The films were layer by layer deposited on substrate (silica glass) using the dip-coating technique. The thickness of the layers were controlled by viscosity of the solutions and withdrawing speed parameters. After specific annealing, in air, the samples were characterized by scanning electron microscopy SEM, spectroelipsometry SE, X-ray photoelectron spectroscopy XPS, Raman spectroscopy. A more thoroughly control of the processing parameters seems to be essential in obtaining BiFeO3 thin films. Solution chemistry variations (differences in precursor type) can have a significant impact on the film properties. [Copyright &y& Elsevier]

Abstract: Owing to their peculiar characteristics, bismuth oxides are used in various domains, such as microelectronics, sensor technology, optical coatings, transparent ceramic glass manufacturing, etc. Bismuth oxide system exhibit high oxide ionic conductivity and have been proposed as good electrolyte materials for application, such as solid oxide fuel cell (SOFC) and oxygen sensor. Antimony doped and undoped Bi2O3 films were deposited onto glass substrate from bismuth nitrate and antimony precursor solutions. As chelating agent polyethyleneglycol (PEG) was used and the above-mentioned precursor solutions were sufficiently viscous. In the present paper, the formation of different phases belonging to Bi–O system during thermal treatments of the Bi-based films is investigated by means of spectroscopic ellipsometry (SE), polarising microscope observation, X-ray diffractometry (XRD), and infrared spectrometry (IR). The thickness and the porosity of the films were evaluated. These preparation techniques, differing mainly in precursor materials and method of deposition, lead to different quality of the resulting films. [Copyright &y& Elsevier]