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Indium sulfide thin films with different amounts of silver doping were deposited by spray pyrolysis. The samples were tested as potential photocatalysts by degrading methylene blue (MB) dye aqueous solution under the effect of light. Samples were prepared using precursors with Ag/In ratios of 0 at.%, 4 at.%, and 6 at.%, corresponding to a measured and normalized Ag concentration in the films of 0.0 at.%, 1.4 at.%, and 2.3 at.%, respectively. Scanning electron microscopy revealed that the surface of the films was homogeneous and compact. Within the energy resolution of dispersive x-ray spectroscopy, the films were revealed to be stoichiometric with an S/In ratio of 1.50 ± 0.05. The films exhibited semiconductor behavior, and the best direct-current (DC) conductance was achieved for the film with 1.4 at.% Ag doping. Changes in the Ag concentration led to the activation of different conduction mechanisms, from correlated barrier hopping (for the undoped and for 1.4 at.% Ag-doped film) to overlapping large-polaron tunneling (for the 2.3 at.% Ag-doped film). After immersing the samples in MB solution and exposing them to visible light for 270 min, a significant decrease of the MB absorption was observed. The lowest absorption (and thus highest photodegradation efficiency) was measured for the solution containing the sample with 1.4 at.% Ag doping, showing a photodegradation efficiency of 83%. Considering their performance and relatively low manufacturing cost, such In2S3:Ag films could contribute to the solution of environmental problems related to wastewater via photodegradation of contaminants under illumination by sunlight.

A set of silver-doped indium sulphide (In2S3:Ag) thin films were deposited by spray pyrolysis technique, at 350 degrees C, to analyze the effects of the Ag doping on the physical properties of the films. Within the limits of the analyzed dopant concentration, X-ray diffraction (XRD) revealed the polycrystalline nature of the films, crystalizing in the beta-In2S3 cubic phase, regardless the level of doping. Both XRD and Raman spectroscopy confirmed the absence of secondary phases. Optical absorption spectra evidenced that the films are opaque to ultraviolet radiation, but transparent in visible and near infrared regions of the electromagnetic spectrum. According to absorption and extinction coefficients variations, the films are smooth and homogeneous. The forbidden bandgap (E-g) increases with increasing Ag concentration. Photoluminescence measurements reveal that the films exhibit seven emissions related to In2S3 defects. The films are semiconductor and the transport phenomena are assisted via small polaron hopping. The photovoltaic effect in Ag/In2S3(n)/Si(p)/Ag is confirmed by I-V characterization in dark and under illumination., This research was partly supported by the projects HP-NANOBIO Project PID2019-111163RB-100, granted by Spanich Ministry of Science, and Project CIVP18A3940, granted by Fundación Ramón Areces, Spain. CVV thanks Xunta de Galicia (Spain) for the AEMAT (ED431E-2018/08) Strategic Partnership and the use of RIAIDT-USC analytical facilities. CVV belongs to the Galician Competitive Research Group ED431C-2017/22, co-funded by FEDER. Part of this work was also supported by the Portuguese Foundation for Science and Technology (FCT) in the frame work of the Strategic Funding UIDB/04650/2020.

Inorganic two-dimensional semiconductor indium sulfide (In2S3) has recently attracted considerable attention as a buffer material in the field of thin-film photovoltaics, photo electrochemical cells and other energy-related applications. Compared with this growing interest, however, detailed characterizations of the commercial material are not done. The present investigation deals with the systematic investigation of the physical properties of powdered β-indium sulfide (In2S3). The crystalline structure, the composition, and the morphological properties of the samples were characterized using a range of techniques such as X-ray powder diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). X-ray diffraction patterns revealed mixed peaks of In2S3 and In2O3 for the sample annealed at 400 °C. The In2O3 peaks were crystalline with a cubic phase with a (222) preferential orientation. These results were supported by the FTIR, and XPS studies. Thus, a significant correlation was established between the annealing temperature and the TEM images. The main conclusion of the paper opens the possibility of using In2S3 layers for solar cells.

La0.7Ga0.3Fel-xTixO3 (x = 0, 0.1, 0.2, and 0.3) polycrystalline compounds were successfully prepared using the solid–solid process. The structural study proves that the samples are centrosymmetric ...

Indium sulfide (In2S3) thin films have been synthesized on glass substrates using the spray technique (CSP). The S : In molar ratio was varied from 1 to 4 in the starting solution. The Raman analysis confirms the formation of the β-In2S3 material and the absence of a secondary phase. The EDS analysis reveals that our layers are pure. The thin film surface is free of cracks, as observed in AFM images. Optical transmission achieved 80% in the visible and near infrared region. The refractive index (n) is affected by the changes in the S/In molar ratio. The optical parameters, single oscillator energy (E0), dispersion energy (Ed) and high frequency dielectric constant (e∞), are calculated via the Wemple–DiDomenico model. In addition, the photoconductivity kinetics in In2S3 films for S/In = 2 were investigated and analyzed. The I–V characteristics and the photoresponse were also studied.

Indium sulfide thin films, doped with silver, were synthesized by spray pyrolysis technique. These samples were subsequently annealed in air and in vacuum, at the temperature of 400 ◦C, for 2 h. This work reports the effect of the thermal treatments on the structure, morphology and optical characteristics of the films, but also the study of the photodegradation efficiency of methylene blue solution. The as-produced films are polycrystalline, exhibiting the tetragonal β-phase structure of In2S3. The annealing treatments cause an increase of 27% and 74% of the crystallite size, and of the roughness of the films (20% and 56%), for the vacuum and air annealed samples, respectively, but provoke a significant decrease of the optical transmittance. The optical band gap decreases from 2.71 eV in the as-produced film, to 2.45 eV and 2.39 eV in the vacuum and air-annealed films, respectively. The photodegradation efficiency of the methylene blue solution increases from 83.0% for the as-produced film to around 95.4%, regardless the type of annealing., Grant of the Romanian Ministry of Education and Research, CNCS - UEFISCDI, project number PN–III–P1-1.1-TE-2019-1209, within PNCDI III

In this work, nano-silver synthesized with mango leaf extract as a reducing agent was doped onto synthesized zeolite A (SZA), produced from Nigerian kaolin via green synthesis route. The produced a...

La0.6Ga0.4Fe1-x MnxO3 compounds (x = 0, 0.1, 0.2 and 0.3) have been prepared using solid state reaction route. Structural, optical and electrical properties of the elaborated samples have been investigated in order to establish the effect of doping by manganese. The X-ray diffraction study implies that replacing Fe with Mn forces no phase transition. They have an orthorhombic structure with different sizes of crystallites. Optical measurements prove that the optical band gap Eg increases from 2.72 eV to 3.25 eV when increasing the manganese content. Also, electrical characterization shows that the conductivity is dependent on Mn concentration. Conduction process is found to be thermally activated. Then, small polaron hopping is the appropriate conduction mechanism. The temperature dependence of the exponent “n” indicates that the CBH model governs the conductivity over dispersive region. Impedance response of undoped sample is found to be different from the doped ones. But, for all investigated samples, grain boundary is more resistive than grain. The inferred activation energy (Ea) from the conductivity, the relaxation time and the grain boundaries are closed to each other. Also, it si found that Ea values vary similarly as a function of manganese content.

In2S3 thin films were grown on indium tin oxide (ITO) glass substrate by chemical spray pyrolysis technique at 360°C. The structural analysis of the deposited films shows a combination of tetragonal and cubic structures. The average crystallite size is about 25 nm. The electrical properties of In2S3 thin films have been investigated in a wide frequency (40Hz-100MHz) and temperature (400 K-660 K) ranges.We find that the electrical conductance of the In2S3 thin films is frequency and temperature dependent. The dc conductance shows a semi-conductor behavior for In2S3 films over the explored range of temperature and it follows the Arrhenius law with different activation energies. The variation of ac conductance and the frequency exponent `s’ are explained by the correlated barrier hopping (CBH) model. The Nyquist plots of impedance exhibit semicircle arcs and an electrical equivalent circuit has been suggested to interpret the impedance results.

Indium sulfide (In

Sn2Sb2S5 materials were synthesized by thermal evaporation using earth-abundant tin, antimony and sulfur elements. The effect of annealing temperature on structural, morphological, optical, thermal and electrical characterization was obtained using many techniques. The deposited films were annealed in air for 1 h at 100 °C and 300 °C. X-ray diffraction analysis reveals that while as-deposited films are amorphous, a crystallized phase, with an orthorhombic crystalline structure, appears after annealing. Via the photothermal deflection spectroscopy, the sub-bandgap energy decreased from 1.98 to 1.75 eV with rising the annealing temperature. Besides, static and dynamic thermal properties of as deposited and annealed Sn2Sb2S5 thin films were measured using electropyroelectric method. It was observed that an increase (40.5–46.5 W m−1 K−1) was found for the thermal conductivity values by increasing annealing temperature, while thermal diffusivity decreases from 12.1 × 10−6 to 9.31 × 10−6 m2 s−1. Moreover, Nyquist spectra performance in the temperature range 300–540 K revealed the presence of a relaxation phenomenon in the microstructure of the studied sample. In addition, the level of the peaks is crashed with temperature, showing that the charge carriers are thermally activated. Finally, Sn2Sb2S5 thin film annealed at 300 °C was found the best sample for use in optoelectronic and solar cell devices. This work suggests a low cost promising compound for scalable synthesis of Sn2Sb2S5 thin films for solar cell and photovoltaic applications.

Silver doped indium sulfide (In2S3:Ag) thin layers were prepared by spray pyrolysis. The Ag concentration varies in the range of 0–6 at%. The X-ray diffraction (XRD) indicates the presence of cubic phase of β-In2S3 and the crystallite size values exhibit a maximum at an Ag concentration of 4%. In addition, morphological analysis by atomic force microscopy (AFM) shows that the film surface is continuous, compact, free of cracks and depends on the Ag concentration. This observation is remarkable by evolution of surface roughness values. The films reveal a semiconductor behavior. This is observed because the electrical conductance increases with the increase of measurement temperature and the analysis of the Nyquist diagram shows the appearance of half circles, whose radius decreases by increasing the temperature from 300 K to 600 K. The electrical equivalent circuit of undoped In2S3 and In2S3:Ag4% at 460 K and 470 K contains two components connected in serial. The first is composed of a resistance R1, an inductance L and a constant phase element CPE1 in parallel and the other covers R2 and a constant phase element CPE2 that are connected in parallel. Inductive and capacitive effects exist in these materials and they depend on frequency. For Ag concentration equal or greater than 4%, the equivalent circuit is a parallel association of a resistor with a constant phase element. The activation energy is minimum for an Ag concentration of 4%., This work was supported by Spanish Ministry of Science and Innovation, Spain - Grant ID: CTQ2016-79561-R (MODENA), Fundacion Ramon Areces, Spain -Grant ID: CIVP18A3940 and Xunta de Galicia, Spain - Grant IDs: Galician Competitive Research Group ED431C-2017/22, AEMAT Strategic Partnership ED431E-2018/08. Authors would like to thank the use of RIAIDT - USC analytical facilities.

The annealing temperature (Ta) dependence of the structural, morphological, electrical and dielectric properties of ZnS thin films was investigated. In this work, we consider the as-deposited and annealed ZnS thin films at different temperatures. The as-deposited films were amorphous in nature. However, the films annealed at Ta ≥ 673 K, exhibited a hexagonal structure with (002) preferential orientation. The post annealing caused an improvement in crystallinity. The best one was observed at Ta = 723 K. Grain size increased from 7 nm to 25 nm as annealing temperature was increased from 673 K to 723 K. The surface of annealed samples is homogenous and uniform and the rms roughness is dependent on the annealing temperature: it increases with temperature within the range 5–50 nm. The film electrical conductance is found to be dependent on frequency measurement and annealing temperature: the dc conductance exhibits semi-conductor behavior for all ZnS films over the explored range of temperature and the conductance was found to enhance with increasing annealing temperature up to 623 K. In addition, it was observed that the highest conductance and lowest activation energy of ZnS films were obtained at an annealing temperature of 623 K. The mechanism of alternating current ac conductance can be reasonably explained in terms of the overlapping-large polaron tunnelling (OLPT) model for samples annealed at 623 K and 673 K. To our knowledge, this conduction mechanism was rarely found in chalcogenide materials. A significant change of Nyquist plot with annealing temperature was noted permitting the correlation between the microstructure and its electrical properties. The impedance analysis investigated that the relaxation process is well pronounced for the both annealed films at 623 K and 673 K. The dielectric behavior was associated to the polarization effect, an improvement on the dielectric constant ε′ and dielectric loss ε′′ with annealing was noticed. This work was supported by Tunisian Ministry of Higher Education and Scientific Research, Spanish Ministry of Science and Innovation – FEDER Funds (MODENA Project CTQ2016- 79461-R) and Fundaci´on Ram´on Areces (Spain, ProjectCIVP18A3940). NANOMAG group belongs to Galician Competitive Research Group ED431C-2017/22, programme co-funded by FEDER, and AEMAT Strategic Partnership (ED431E-2018/ 08, Xunta de Galicia, Spain). SI

Barium titanate is one of the most studied perovskite materials owing to its ability to the substitution in both sites, to its high dielectric constant and to its stability. It is characterized by a diversity of remarkable properties, especially ferroelectric and dielectric properties, which can be improved by doping, making this material suitable for many applications. We have investigated the effect of calcium ion substitution on the structural, optical, electrical and dielectric properties of this compound. Ba0.9Ca0.1TiO3 ceramic was elaborated using the solid-state diffusion method. This compound crystallized in the tetragonal phase with a crystallite size of 22 nm. Fourier transform infrared spectroscopy measurements revealed that octahedral vibrations are affected by Ca incorporation. Electrical analyses show that the compound has a semiconductor behavior, and that both grains and grain boundaries are responsible for the thermal evolution of the conduction mechanisms. Two different transition temperatures were detected. One of them coincides with the Curie temperature, which is confirmed by dielectric measurements. The compound shows a high dielectric constant up to 420 K which is seemingly constant in a wide frequency range. Such behavior is sought for the development of energy storage devices.

We report the results of first-principles calculations based on the full-potential linearized augmented plane wave (FP-LAPW + lo) method to explore the effects of alloying under the non-conventional AlN III–V compound with bismuth. We have calculated the structural and electronic properties of the binary compounds AlN and AlBi in the zinc blend structure. We have found a good agreement between our results and the experimental and theoretical results available for that binary compounds which may be a support for the results of the ternary alloys. For the AlNBi ternary alloys, we have found a rapid reduction of the energy gap by 1.31 eV/%Bi accompanied by a strong increase in the spin–orbit splitting energy (Δso) with increasing Bi composition. We have also shown that the Δso becomes greater than the energy gap for composition of Bi about 4.2% (Δso > E g). This result is significant due to the possibility of suppressing Auger recombination, which is expected to improve the high temperature performance and thermal stability of light emitting devices. Finally, we have calculated the variation of the optical properties of AlNBi compounds, such as dielectric function and refractive index versus Bi composition.

In the present work, we have deposited Ga-doped ZnO (GZO) thin films by magnetron sputtering technique using nanocrystalline particles elaborated by sol–gel method as a target material. The effect of the thickness, on the physical properties of the GZO thin films was analyzed. The influence of the thickness, on structure, surface morphologies, chemical atomic composition, electrical and optical properties was investigated by XRD, SEM, TEM, AFM, Raman measurement, Hall measurement and UV Vis-NIR spectrophotometer, respectively. X-ray diffraction (XRD) results revealed the polycrystalline nature of the films with hexagonal wurtzite structure having preferential orientation a long [002] direction normal to the substrate. The lowest resistivity obtained from electrical studies was 10 - 4 Ω cm. The optical properties were studied using a UV–vis spectrophotometer and the average transmittance in the visible region (400–800 nm) was found to be 90%.

Different processes are used to improve the deposition of a nanocrystalline silicon layer to enhance optical absorption in different devices. The difficulty encountered lies in the reproducibility and cost of the process. In the present study, we have investigated the effect of a crystalline seed layer on the structural properties of a subsequent hydrogenated silicon (Si:H) layer (top layer). Structural properties of deposited films were investigated by absorption and Raman spectroscopy, grazing incidence X-ray diffraction measurements and spectroscopic ellipsometry. They show that using the seed layer approach promotes the structural evolution of the subsequent layer by improving its size and fraction of crystallites. UV–visible reflectance spectra simulations using Bruggeman effective medium approximation were used in order to investigate the composition evolution of the studied samples. They predict that the optical model of the elaborated layers consists of (i) the crystalline substrate (ii) the incubation layer (a mixture of amorphous silicon and voids) (iii) the bulk crystalline layer (a mixture of amorphous silicon, crystalline silicon and voids) and finally (iv) the surface layer. The incubation layer observed at the beginning of growth of the subsequent layer is absent in the optical model in the presence of the seed layer or it may be very thin in thickness, so that it has not been presented in the optical model. The optical model shows also an increase of void fraction in the top layer in the presence of the seed layer; this has been linked to the increase of crystallite size. It is noted also that the top layer is rougher in the presence of the seed layer and this has been attributed to the presence of larger silicon crystallites on its surface. Such deposition process can be used to enhance crystalline phase in absorber layer for optoelectronic devices.

Transport properties of Pr0.7Ca0·3Mn0·85Cr0·15O3(Cr-PCMO) manganite have been studied in a large frequency and temperature ranges by mean of impedance spectroscopy. The conductance spectra are discussed in the outline of a double and single Jonscher laws for the temperature ranges [80 K–110 K] and [120–170 K] respectively. The correlated barrier hopping and the non small polaron tunneling (NSPT) conduction models are used to explain the dynamic of charge carriers in the ac regime. The lower temperature range is characterized by the coexistence of such two conduction processes. Below the frequency ν = 105 Hz, the compound exhibits a semiconductor behavior with no detectable electrical transition. A metal - semiconductor transition at around T = 190 K was observed at high frequency range (ν = 2.106 Hz). Beyond the Debye temperature, θD/2 = 130 K, the small polaron hopping (SPH) conduction process is thermally activated. Over the investigated frequency interval ν ≤ 105, the activation of the SPH conduction process needs the same activation energy Ea1 = 112 meV. At lower temperature range, the interaction between electron and acoustic phonon becomes important, the variable range hopping (VRH) mechanism was activated via a disorder energy WD. The temperature dependence of the local energy proves that type of the VRH process is sensitive to the frequency parameter and the investigated temperature range. The hopping and the disorder energies are strongly sensitive to frequency.

Contains fulltext : 177598.pdf (Publisher’s version ) (Closed access) OBJECTIVES: Excessive fluid therapy in patients with sepsis may be associated with risks that outweigh any benefit. We investigated the possible influence of early fluid balance on outcome in a large international database of ICU patients with sepsis. DESIGN: Observational cohort study. SETTING: Seven hundred and thirty ICUs in 84 countries. PATIENTS: All adult patients admitted between May 8 and May 18, 2012, except admissions for routine postoperative surveillance. For this analysis, we included only the 1,808 patients with an admission diagnosis of sepsis. Patients were stratified according to quartiles of cumulative fluid balance 24 hours and 3 days after ICU admission. MEASUREMENTS AND MAIN RESULTS: ICU and hospital mortality rates were 27.6% and 37.3%, respectively. The cumulative fluid balance increased from 1,217 mL (-90 to 2,783 mL) in the first 24 hours after ICU admission to 1,794 mL (-951 to 5,108 mL) on day 3 and decreased thereafter. The cumulative fluid intake was similar in survivors and nonsurvivors, but fluid balance was less positive in survivors because of higher fluid output in these patients. Fluid balances became negative after the third ICU day in survivors but remained positive in nonsurvivors. After adjustment for possible confounders in multivariable analysis, the 24-hour cumulative fluid balance was not associated with an increased hazard of 28-day in-hospital death. However, there was a stepwise increase in the hazard of death with higher quartiles of 3-day cumulative fluid balance in the whole population and after stratification according to the presence of septic shock. CONCLUSIONS: In this large cohort of patients with sepsis, higher cumulative fluid balance at day 3 but not in the first 24 hours after ICU admission was independently associated with an increase in the hazard of death.

Tin-doped indium sulfide (In2S3:Sn) thin films with different Sn:In molar ratios (0% to 1% by mol in solution) have been deposited on glass substrates by a chemical spray pyrolysis method. The films were investigated by x-ray diffraction analysis, optical absorption, Raman, and photoluminescence spectroscopies, field-emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, and atomic force microscopy. The structural properties revealed that the In2S3:Sn thin films had polycrystalline cubic structure with average crystallite size increasing from 16.3 nm to 25.5 nm. The surface morphology of the films was continuous and crack free. The average and root-mean-square roughness increased from 13.12 nm to 31.65 nm and from 16.14 nm to 39.39 nm, respectively, with increasing Sn:In molar ratio. Raman studies revealed the presence of vibration modes related to In2S3 phase, with no signature of secondary phases. The transmission coefficient was about 65% to 70% in the visible region and 70% to 90% in the near-infrared region. The optical bandgap values for allowed direct transitions in In2S3:Sn were found to lie in the range from 2.68 eV to 2.80 eV. The refractive index of the In2S3:Sn thin films decreased from 2.45 to 2.37 while the k values lay in the range from 0.02 to 0.25 for all wavelengths. Defect-related photoluminescence properties are also discussed. These In2S3:Sn films are promising candidates for use in optoelectronic and photovoltaic devices.

Tin doped In2S3 film was grown by chemical spray pyrolysis method using compressed air as a carrier gas. Structural, morphological, optical and electrical properties of film have been investigated. X-ray diffraction shows well crystallized film according to cubic β-In2S3 phase. The FESEM photograph reveals that the film is dense without pinholes. The average surface roughness and the root-mean square roughness are about 18 and 14 nm, respectively. Optical transmission is more than 60 % in visible region and 85 % in infrared one. Direct band gap energy of 2.62 eV has been found. The impedance plane plot shows semicircle arcs and an electrical equivalent circuit has been proposed to explain the impedance results. We have performed ac and dc conductivity studies inspired from Jonscher and correlated barrier-hopping models. These studies helped establishing significant correlation between temperature and activation energy. From the impedance spectroscopy analysis, we investigated the frequency relaxation phenomenon and the equivalent circuit of such thin film.

Zinc-doped In2S3 thin films have been deposited by spray pyrolysis method at 350 °C on glass substrates with ITO contacts. The samples were sealed under vacuum (10−3 Torr) into a Pyrex tube and then annealed for 2 h at temperatures ranging from 300 to 450 °C with a step of 50 °C. The effect of the annealing temperature (Ta) on structural, morphological and optical properties of the In2S3 films was studied. The films, annealed at Ta ≤ 300 °C, result in films that consist of tetragonal β-In2S3 phase with (220) preferential orientation, while for films annealed at Ta > 300 °C, a structural transition from tetragonal to cubic β-In2S3 occurs with (400) preferential orientation. The film grain size decreases from 42 to 33 nm. The surface morphology analysis reveals that the films annealed at 300 °C present an average roughness of 40 nm. The optical band gap is found to be direct and it decreases with the increase of annealing temperature. A higher optical transmittance of 80 % is obtained at Ta = 350 °C.

CuIn1-xGaxSe2 (CIGS) nanoparticles have been successfully fabricated by using a relatively simple and easy handling solvothermal process in the solvent of N, N dimethylformamide (DMF). A probable formation mechanism of chalcopyrite quaternary semiconductor nanoparticles is proposed. Structural, morphological and optical properties of prepared nanoparticles CIGS (x = 0, 0.3, 0.6, 0.8 and 1) were analyzed. The synthesized product is of ordered chalcopyrite structure, with the particle size in the range of 15–25 nm Cu2Se secondary phases was detected by XRD for the sample with x = 1, which is also affirmed by Raman spectra. Cathodoluminescence measurements allowed us to observe a high emission which can be attributed to a band to band transition, and the possible energy gap was discussed. The absorption spectra showed strong absorption in the entire visible light to near-infrared region. All results suggested that the as-prepared CIGS nanoparticles were good light absorber layer material for thin film solar cell applications.

Barium titanate is a very attractive perovskite given its ferroelectric, piezoelectric and dielectric properties. These can be further improved by the substitution of barium and titanium by different elements. Introducing both rare earths and/or metals in this compound enhances its optical and electrical properties, thus making it a multifunctional material suitable for many different applications. In the present work, the compound Ba0·91Er0·1/3Ca0·04Ti0·92Sn0·08O3 is prepared by solid state reaction and its structural, morphological, thermal optical and electrical properties are investigated in detail by X ray diffraction, scanning electron microscopy, differential scanning calorimetric, absorption spectroscopy and impedance spectroscopy respectively. Scanning electron microscopy shows that the material is composed by a major polycrystalline phase with micrometric grain size. Two-phase transitions at 448 K and 572 K are deduced from thermal and electrical measurements. The optical measurements indicate that both erbium and tin are well introduced in the structure, which is confirmed by energy dispersive spectroscopy, and affects the vibrational modes. a. c. and d. c. electrical measurements show that, depending on the measurement temperature range, conduction mechanism is either a non-overlapping small polaron tunneling or a correlated barrier hopping model. . Moreover, dielectric measurements prove a high dielectric constant and identify a phase transition from the ferroelectric phase to paraelectric one which is in agreement with literature. Such substitution improves the compound properties and makes it suitable for different devices.

Polycrystalline ytterbium modified bismuth titanate Bi4-xYbxTi3O12 (x = 0, 0.1, 0.2, and 0.3) solid solutions have been synthesized using a solid state reaction method. The effect of varying the ytterbium content on the structural, morphological, vibrational, and impedance properties of this ceramic have been investigated. According to the experimental results obtained from scanning electron microscopy combined with energy dispersive X-ray analysis, a highly dense grain structure and a randomly oriented plate-like morphology were observed, showing an increase in the material grain size with Yb content. Besides, all the samples were found to be free from any other secondary phase. By means of Raman spectroscopy, it was observed that (Bi2O2)2+ layers remain unaffected with composition variation. These observations prove that Yb3+ substitution for Bi3+ occur predominantly, not only in pseudo-perovskite (Bi2Ti3O12)2- sites, but also in (Bi2O2)2+ layers, leading to cationic disorder and to a decrease in the TiO6 octahedral distortion. Raman measurements show also that all compounds exhibit a perovskite-type orthorhombic structure. This latter result is consistent with Fourier transform infra red analysis, which shows the appearance of two absorption bands below 830 cm−1. The optical band gap obtained from UV–visible spectroscopy has been found to slightly decrease from 3.1 to 3.04 eV with increasing Yb3+ substitution from x = 0 to x = 0.3, respectively. The thermal stability was also investigated. It was found from the differential scanning calorimetry that the Curie temperature (Tc) shifted backwards with increasing Yb content. No significant weight loss was found in the thermo-gravimetric analysis curve up to 800 °C temperature. Besides, the impedance spectroscopy studies show a non-Debye-type relaxation and a relaxation frequency shift to higher side with the increase in temperature. The Nyquist plot shows overlapping semicircles which indicate the existence of both grain and grain boundary effect in the prepared ceramic.

Thin layers of indium sulphide with different concentration of chlorine were deposited on substrates of glass, heated at a temperature of 350 °C, by using technique spray pyrolysis. We studied the effect of incorporation of chlorine in the layers on their structural, optical and the photoconductivity properties. X-ray diffraction indicates that our layers are polycrystalline and crystallize in cubic phase β-In2S3 with unit lattice length of a∼10.67 A. We found that the crystallite size is between 10 and 13 nm. From the optical study, the transmittance is around 80 % whereas the energy of band gap increased from 2.53 eV to 2.72 eV with the fraction of chlorine. Even though the photoconductivity study shows that our layers are slightly sensitive to light, they can be used for photovoltaic and optoelectronic applications by enhancing their photosensitivity.

In this study, high purity and near stoichiometric CuInSe2 (CIS) nanoparticles have been successfully synthesized using solvothermal route. The goal of this paper is to improve the crystal quality while reducing production cost and limiting the toxicity of solvothermal reaction, as compared to processes including selenization step. Therefore, the starting solution solvothermal is constituted by the following precursors (CuSO4.5H2O, InCl3.xH2O and Se powder) which were dissolved in N, N Dimethylformamide (DMF) as solvent. A reasonable possible mechanism for the growth of CIS nanoparticles is proposed. The effect of process parameters on the synthesis and characterization of CIS nanoparticles were examined including reaction temperature (165–240 °C), process time (12–24 h) and the drying route. The as-obtained CIS nanoparticles are analyzed using diverse techniques such as x-ray diffraction (XRD), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), Raman spectroscopy and UV–vis-IR spectrophotometer. All results demonstrate that the optimal conditions for preparing a single-phase CIS obtained at 220 °C for 24 h and followed by annealing at 400 °C for 30 min under a nitrogen atmosphere. In addition, XRD results showed that the CIS nanoparticles crystallize in the chalcopyrite structure, with grain size in the order of 25 nm, which is also confirmed by TEM images. Raman spectra show the intense peak at 171 cm−1, which correspond to the chalcopyrite structure, no signature of secondary phases. Optical measurements revealed strong absorption in the entire visible light to near-infrared region and band gap (≈1.04 eV) is very close to those of absorbent materials in thin film solar cells.

ZnS thin films were deposited on glass slides by spray pyrolysis technique. The starting solution is a mixture of zinc chloride and thiourea. The substrate temperature was fixed at 350 °C. The films were then annealed in the temperature range 300–450 °C. Their thickness lies between 560 and 680 nm. We investigate the effect of this annealing on ZnS structural, morphological and optical properties. XRD analysis indicates that ZnS films have a nanocrystalline hexagonal structure with (002) preferential orientation. The grain size increases from 7 to 22 nm with annealing temperature. AFM images indicate a better crystalline phase for the films annealed at 450 °C. The films show homogeneous, uniform distribution and surface roughness varying from 5 to 50 nm. The ZnS films exhibit transparency over 60–85 % in the visible and infrared region. The refractive index lies in the range 1.95–2.20. The band gap energy decreases from 3.76 to 2.65 eV for direct transitions. All results have been discussed in terms of annealing temperature. Furthermore, a ZnS/Si heterojunction was also fabricated by depositing n-type ZnS film on p-type Si substrate using spray method. The performance of the heterojunction was reported.

In2S3 films have been grown on glass substrates by spray pyrolysis technique. The deposition was carried out in a 300–500 °C substrate temperature and the molar ratio S/In is fixed to 2. The characteristics of these films have been determined by X-ray diffraction, energy dispersive spectroscopy, atomic force microscopy and spectrophotometer. These properties are related to the substrate temperature. X-ray diffraction spectra show that the films are polycrystalline and the obtained material is In2S3 with a cubic phase and oriented preferentially towards (400). The film grain size increases from 25 to 31 nm whereas the microstrain decreases from 4.68 × 10−3 to 3.85 × 10−3 with increasing substrate temperature. The average surface roughness passes through a minimum at 340 °C. Optical transmission of 80 % has been achieved in the visible and near infrared regions. The band gap energy has been found in the range of 2.33–2.65 eV. The static refractive index n(λ), the oscillation energy gap E0 and the dispersion energy Ed were determined by the Wemple-Didomenico model. The complex dielectric constants of In2S3 films have been calculated in the investigated wavelength range. It was found that the refractive index dispersion data obeyed to the single oscillator of the Wemple-Didomenico model, from which the dispersion parameters, the oscillation energy values and the high-frequency dielectric constant were determined. Hall effect measurements were carried out for higher substrate temperatures.

In2S3 thin film was prepared by chemical spray pyrolysis technique onto clean soda–lime glass substrate. Indium chloride and thiourea were used as reagents. This film was sealed into Pyrex tube at a pressure of 10−6 Torr and then annealed at 673 K for 3 h. The film was characterized by means of X-ray diffraction (XRD), atomic force microscope (AFM) and by impedance spectroscopy measurements. XRD spectra show that In2S3 film is polycrystalline with a cubic phase and preferentially oriented towards (400). The film grain size is about 45 nm. AFM analysis shows that root mean square (RMS) roughness is equal to 112 nm. The film electrical conductance is found to be dependent on measurement temperature and frequency. The direct current conductivity measurement outlines the dominance of the hopping mechanism. The alternating current electrical conductivity of the sample is controlled by the correlated barrier hopping conduction mechanism. The activation energy is found to be in the order of 90 meV. Furthermore, the film exhibits a photoconductive behavior.

Tin-doped In2S3 films were grown by the chemical spray pyrolysis method using compressed air as a carrier gas. Tin is incorporated in the solution using SnCl4. Structural and optical properties of films were investigated by x-ray diffraction (XRD), absorption, Raman and photoluminescence spectroscopies. Field emission scanning electron microscopy (FESEM) and energy dispersive x-ray spectroscopy were used to explore the surface morphology. The properties of In2S3 thin films are influenced by Sn doping. XRD studies revealed that the deposited films were polycrystalline in nature exhibiting cubic structure and oriented preferentially towards (111). According to FESEM, the surface morphology of the films was free of defects. Raman studies showed different peaks related to In2S3 phase and did not show any secondary phases of In-Sn and Sn-S. In2S3:Sn films exhibited transparency over 60–85% in the visible and infrared regions. The optical band gap was found to vary in the range 2.71–2.58 eV for direct transitions. The room temperature photoluminescence (PL) studies revealed two PL bands, centered at 529 nm (band A) and 725 nm (band B). From these results, one can conclude that our material can be used as transmittive windows in low-cost solar cells. The conductance and capacitance characterization at ambient temperature were also investigated and gave interesting physical properties for photovoltaic applications.

Tin-doped In2S3 films were grown by the chemical spray pyrolysis method using compressed air as a carrier gas. The films were annealed for 2 h at different temperatures (300, 400 and 500 °C) under nitrogen atmosphere. X-ray diffraction data show that In2S3:Sn films are polycrystalline with a cubic phase. The film grain size increases from 26 to 37 nm. The residual microstrain and dislocation network reach the values 3.08 × 10−3 and 0.73 × 1011 lines cm−2, respectively, at the annealing temperature of 500 °C. Transmittance decreases with increasing temperature. It varies in the range of 65–85 % in visible and infrared regions. The optical band gap is found to vary in the range 2.4–2.85 eV for direct transitions. The best surface state is obtained at 400 °C. The RMS roughness was estimated to be 39.4–19.8 nm. Electrical measurements at room temperature show that the sheet resistance decreases down to 130 Ω at 500 °C. The conductance and capacitance characterization at ambient temperature are also investigated and give interesting physical properties for photovoltaic applications.

International audience; In the present work, we have deposited gallium doped zinc oxide thin films by magnetron sputtering technique based nanocrystalline particles elaborated by sol–gel method. In the first step, the nanoparticles were synthesized by sol–gel method using supercritical drying in ethyl alcohol. The structural studied by X-ray diffractometry indicates that GZO has a polycrystalline hexagonal wurzite structure with a grain size of about 30 nm. Transmission electron microscopy measurements have shown that very small particles of GZO are present in the aerogel powder. Then, thin films were deposited onto glass substrates by rf-magnetron sputtering at ambient temperature. The influence of RF sputtering power on structural, morphological, electrical, and optical properties were investigated. It has been found that all of the films deposited were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The film deposited at 60 W showed the lowest electrical resistivity of 3.5 × 10−3 Ω cm achieved through the highest Hall mobility of 9.30 cm2 V−1 s−1. All the GZO films in this study showed the optical transmittances higher than 80 %.

Solar cells based on transparent conductive oxides such as ZnO/Cu2O constitute a very advanced way to build high-performance cells. In this work, we are interested in the characterization of the interface through nanoscale modeling based on ab initio approaches (density functional theory, local density approximation, and pseudopotential). This work aims to build a supercell containing a heterojunction ZnO/Cu2O and study the structural properties and the discontinuity of the valence band (band offset) from a semiconducting to another phase. We build a zinc oxide in the wurtzite structure along [0001] on which we place the copper oxide in the hexagonal (CdI2-type) structure. We choose the method of Van de Walle and Martin to calculate the energy offset. This approach fits well the density functional theory. Our calculation of the band offset gives a value that corresponds to other experimental and theoretical values.

Tin doped In2S3 films were grown by the chemical spray pyrolysis (CSP) method using the pneumatic spray set-up and compressed air as a carrier gas. The spraying solution contained indium chloride (InCl3), thiourea [CS(NH2)2] and (SnCl4) at a molar ratio of S/In = 2.5. The deposition was carried out at 350 °C on glass substrates. The Sn doping level was changed with Sn/In = 0-8 % in solution. The effect of Sn concentration on electrical, optical and structural properties of In2S3:Sn thin films have been investigated.

International audience; Highly transparent conducting Al-doped zinc oxide (AZO) thin films have been grown onto p-type porous silicon substrates by RF-magnetron sputtering at room temperature using aluminum doped nanocrystalline powder. The obtained AZO films were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The films are highly transparent in the visible wavelength region with a transmittance higher than 85% and an electrical resistivity of 1.56 × 10− 4 Ω·cm was obtained at room temperature. On the other hand, we have studied the position of the p–n junction involved in the In2O3:SnO2/(n)AZO/Si(p) structure, by electron-beam induced current technique. Current density–voltage characterizations in dark and under illumination were also investigated. The cell exhibits an efficiency of 5%.

Cuprous oxide is selected as a promising material for photovoltaic applications. Density functional theory is used to study the structural, electronic, and thermodynamic properties of cuprous oxide by using the local density approximation and generalized-gradient approximation. The effect of pressure on the structural and electronic properties of Cu2O is investigated. This study confirms and characterizes the existence of new phases. Hexagonal and tetragonal phases are not completely indentified. We focus on the phase transition of the cuprous oxide under hydrostatic pressure to tetragonal and hexagonal (CdI2) structures. Variation of enthalpy with pressure is used to calculate the pressure of the phase transition.

In2S3 thin films with different S/In molar ratios (from 1.5 to 3.5) were deposited via a spray pyrolysis technique on glass substrates at 340∘C. Then, the obtained films were annealed at the same temperature 400∘C for 2[Formula: see text]h. X-ray diffraction study reveals the formation of cubic [Formula: see text]-In2S3 phase with (400) as preferred orientation. The crystallite size varies in the range 64–97[Formula: see text]nm. Optical analysis exhibits that transmittance in visible and near infrared regions is higher than 65% for all films. The optical band gap varied from 2.58[Formula: see text]eV to 2.67[Formula: see text]eV. The optical parameters (refractive index, extinction coefficient, dielectric constants) were calculated through the transmittance ([Formula: see text]) and reflectance ([Formula: see text]). Dispersion parameters ([Formula: see text], [Formula: see text]), high frequency dielectric constant ([Formula: see text]), refractive index ([Formula: see text]), oscillator length strength ([Formula: see text]), average oscillator wavelength ([Formula: see text]) and optical moments ([Formula: see text]) were determined by Wemple–DiDomenico model. The surface and volume energy losses with photon energy were also calculated. The optical and electrical conductivities were estimated. These properties of In2S3 films are important for photovoltaic applications.

Tin-doped indium sulfide films were grown on glass substrates by spray pyrolysis technique at low different Sn:In atomic ratio in the starting solution and optimum experiment conditions ([Formula: see text]C, S:[Formula: see text]). The tin to indium molar ratio Sn:In was varied from 0 to [Formula: see text] in the solution. The obtained films with 2[Formula: see text][Formula: see text]m of thickness, are perfectly adhered, homogenous and uniform on the substrates. X-ray diffraction study reveals that all the films are formed in [Formula: see text] phase grown preferentially along (400). These films lose the orientation with increasing tin doping level. The crystallite size of undoped film was 48.8[Formula: see text]nm, which increases to 59.2[Formula: see text]nm corresponding to the film grown with Sn:[Formula: see text]. Raman analysis shows different peaks related to In2S3 phase. Optical analysis shows that these films are transparent in the visible and near IR with a transmittance higher than 85%. The optical gap energy is found to be direct and varies from 2.61[Formula: see text]eV to 2.76[Formula: see text]eV with the increase of Sn:In ratio from 0 to [Formula: see text]. The films are [Formula: see text] type and Sn doping improves considerably their conductivity. The photoluminescence behavior of In2S3:Sn films was also studied.

The ZnO/Cu 2 O system has known a recent revival of interest in solar cells for its potential use as a heterojunction able to highly perform under visible light. In this work, we are interested on the characterization of the interface through nanoscale modelization based on ab initio (Density Functional Theory (DFT), Local Density Approximation (LDA), Generalized Gradient Approximation (GGA–PBE), and Pseudopotential (PP)). This work aims to build a supercell containing a heterojunction ZnO/Cu 2 O and study the structural properties and the discontinuity of the valence band (band offset) from a semiconductor to another. We built a zinc oxide in the wurtzite structure along the [0 0 0 1] on which we placed the copper oxide in the hexagonal structure (CdI 2 -type). We choose the method of Van de Walle and Martin to calculate the energy offset. This approach fits well with the DFT. Our calculations of the band offset gave us a value that corresponds to other experimental and theoretical values.

In2S3 thin films were grown by the chemical spray pyrolysis (CSP) method using indium chloride and thiourea as precursors at a molar ratio of S:In=2.5. The deposition was carried out at 350 °C on quartz substrates. The film thickness is about 1 µm. The films were then annealed for 2 h at 550, 600, 650 and 700 °C in oxygen flow. This process allows the transformation of nanocrystal In2O3 from In2S3 and the reaction is complete at 600 °C. X-ray diffraction spectra show that In2O3 films are polycrystalline with a cubic phase and preferentially oriented towards (222). The film grain size increases from 19 to 25 nm and RMS values increase from 9 to 30 nm. In2O3 films exhibit transparency over 70–85% in the visible and infrared regions due to the thickness and crystalline properties of the films. The optical band gap is found to vary in the range 3.87–3.95 eV for direct transitions. Hall effect measurements at room temperature show that resistivity is decreased from 117 to 27 Ω cm. A carrier concentration of 1×1016 cm−3 and mobility of about 117 cm2 V−1 s−1 are obtained at 700 °C.