Effect of Annealing on the Properties of Nanocrystalline CdS Thin Films Prepared by CBD Method

The CdS thin films were deposited on glass substrate by chemical bath deposition (CBD). The effect of annealing temperature on the morphological, structural, optical and electrical properties of the crystalline CdS films were investigated for different annealing temperature (as deposited, 300, 400 and 500 °C).The annealing time is 1 h. The materials have been prepared using simple aqueous solutions containing cadmium sulfate, as source of cadmium, and thiourea as source of sulfur and ammonium hydroxide as the complexing agent. The temperature of the bath was maintained at low temperature of 80 °C. The surface morphological properties studied by SEM and AFM respectively. The structural properties of CdS thin film was studied by X-ray diffraction. The optical parameter such as transmittance and energy band gap of the films with thermal annealing temperature was investigated by UV-Visible spectrophotometer. The variation of band gap values of CdS thin film samples were found to be in the range of 2.37 to 2.5 eV. Electrical resistivity measurements were carried out in four-probe Van Der Pauw geometry at room temperature by the Hall measurement. SEM image confirmed that film of smooth surface morphology

Photoluminescence characterization of Al/Al₂O₃/InP MIS structures passivated by anodic oxidation

Metal-insulator-semiconductor (MIS) structures were produced by electron beam heating evaporation of Al₂O₃ on InP. Polyphosphate thin films with the thickness of 100 to 150 A were used to passivate the interface InP/Insulator. Photoluminescence spectra were obtained at low temperatures at the various stages of MIS-InP structure formation. At ambient temperature, photoluminescence topography made it possible to characterize the surface state after each technological stage. The interface degradation under the effect of repeated annealing is insignificant up to the temperatures close to 350 °C. Major radiative defects detected using photoluminescence spectrum with energies ranged from 0.95 to 1.15 eV were attributed to the impurity complexes of phosphorus vacancies, concentration of which is substantially reduced in the presence of anodic oxide

Hypothesis testing on the planktic foraminiferal survival model after the KPB mass extinction: evidence from Tunisia and Algeria

A historical review of the extinction, survival, and evolutionary models of planktic foraminifera proposed for the Cretaceous/Paleogene boundary (KPB) mass extinction event sometimes leaves the impression that there is still no conclusive evidence to support any single one of them. Two main models have been put forward: i) catastrophic mass extinction, almost total for some authors, compatible with the geologically instantaneous paleoenvironmental effects of a large meteorite impact (Chicxulub impact, Mexico); and ii) gradual mass extinction, compatible with the paleoenvironmental effects of massive, long-lasting volcanism (Deccan Traps, India). Over the years, a lot of evidence has been proposed supporting one hypothesis or the other, highlighting isotopic (delta O-18, delta C-13, Sr-87/Sr-86) as well as taphonomic, biostratigraphic, quantitative (relative and/or absolute abundance), phylogenetic, and even teratological. We review previous planktic foraminiferal and stable isotope studies, and provide new quantitative and statistical tests from two pelagic sections: the El Kef section (Tunisia), recognized as the most continuous and expanded lowermost Danian section worldwide, and the Sidi Ziane section (Algeria), affected by relevant hiatus in the lower Danian. The results indicate that all the latest Maastrichtian planktic foraminiferal species except those of Guembelitria went extinct exactly at the KPB, supporting the hypothesis of an almost total extinction. In the light of this new evidence, we maintain that the Maastrichtian planktic foraminiferal specimens found worldwide in lower Danian samples could be the result of similar reworking and vertical mixing processes to those at El Kef and Sidi Ziane

Properties Study of ZnS Thin Films Prepared by Spray Pyrolysis Method

Zinc sulfide (ZnS) is important II-VI semiconductors material for the development of various modern technologies and photovoltaic applications. ZnS thin film was prepared by using chemical spray pyrolysis technique. The starting solution is a mixture of 0.1 M zinc chloride as source of Zn and 0.05 M thiourea as source of S. The glass substrate temperature was varied in the range of 300 °C-400 °C to investigate the influence of substrate temperature on the structure, chemical composition, morphological and optical properties of ZnS films. The DRX analyses indicated that ZnS films have polycrystalline cubic structure with (111) preferential orientation and grain size varied from 25 to 60 nm, increasing with substrate temperature. The optical properties of these films have been studied in the wavelength range 300-2500 nm using UV-VIS spectro-photometer. The ZnS films has a band gap of 3.89 eV-3.96 eV

Properties Study of ZnS Thin Films Prepared by Spray Pyrolysis Method

Zinc sulfide (ZnS) is important II-VI semiconductors material for the development of various modern technologies and photovoltaic applications. ZnS thin film was prepared by using chemical spray pyrolysis technique. The starting solution is a mixture of 0.1 M zinc chloride as source of Zn and 0.05 M thiourea as source of S. The glass substrate temperature was varied in the range of 300 °C-400 °C to investigate the influence of substrate temperature on the structure, chemical composition, morphological and optical properties of ZnS films. The DRX analyses indicated that ZnS films have polycrystalline cubic structure with (111) preferential orientation and grain size varied from 25 to 60 nm, increasing with substrate temperature. The optical properties of these films have been studied in the wavelength range 300-2500 nm using UV-VIS spectro-photometer. The ZnS films has a band gap of 3.89 eV-3.96 eV

SIMULATION OF A SOLAR DRIVEN AIR CONDITIONING SYSTEM FOR A HOUSE IN DRY AND HOT CLIMATE OF ALGERIA

Solar cooling technology is environmentally friendly and contributes to a significant decrease of the CO2 emissions which cause the green house effect .Currently, most of the solar cooling systems commonly used are the hot water driven lithium bromide absorption chillers. According to the operating temperature of driving thermal source, single – effect Li Br/H2O absorption chillers have the advantage of being powered by ordinary flat-plate or evacuated tubular solar collectors available in the market. The main objective of this work is to develop a computational model that allows the simulation of an hourly basis for an absorption refrigeration - single - effect used the LiBr/H2O as solution working fluid- system assisted by solar energy and natural gas as auxiliary fuel coupled with the residential building located in the hot and dry climate of Algeria. This model will be developed using the dynamic simulation program TRNSYS, considering three specifics areas of work: determination of the cooling loads for a building, implementation of the computational model for the absorption refrigeration system and the parametric optimization of components, which will make possible an approach to optimal sizing of the solar absorption system. The results of the simulation of the absorption chiller indicate that an area of 28 m2 of flat plat collectors with an inclination of 35° and 800 L for hot storage tank provides an annual solar fraction of 80% and a thermal performance coefficient COP of 0.73, getting to cover demand of air conditioning in a house of 120 m2 located in Biskra (Algeria)

Development and Modeling of a Geographic Information Systemsolar Flux Inadrar, Algeria

Algeria is one of the important solar belt countries, withan enormous potential in solar energy. The exploitation andpromotion of these energy resources offers the opportunity oftackling energy-related and economic challenges, and tocontribute to a sustainable development in our countries.Theknowledge and assessment of the available solar energy resourcesis a critical part to renewable energy planning and sizing and canplay an important role in lessen the harmful impacts ofenvironmental problems associated with the recovery of fossilfuels and their use in power stations. However, the majorhandicap has always been the spatial density of radiometricstations which is inadequate. This study aimed to develop solarpotential data estimation in Adrar region located in the warmAlgerian desert region. The data delivered will be implemented inGeographic Information Systems (GIS) and used as support forTechnical analysis of solar potential in this region

XPS, FTIR, EDX, and XRD analysis of Al₂O₃ scales grown on PM2000 alloy

This work is an original example to compare the results obtained after calcination of Al2O3 hydroxides and oxidation of alumino-formers alloys. FTIR and XPS signatures were obtained for various oxidation temperatures and compared with those known from the literature about calcination of Al2O3 precursors. The aim of this work is to evaluate the use of IR spectroscopy and XPS analysis to probe the structural varieties of Al2O3. For this objective, a study of the PM2000 oxidation at various temperatures was conducted by means of XRD, IR spectroscopy, XPS analysis, EDX analysis, and SEM observations. This allowed us to clearly differentiate the transition Al2O3 from the α-Al2O3 and, amongst the transition Al2O3, to differentiate the characteristic of the IR spectrum of γ-δ phases from that of the θ phase