Tarek Ben Nasrallah - Academia.edu (original) (raw)

Papers by Tarek Ben Nasrallah

Physica Scripta

In this study, the structural, electronic, and thermoelectric properties of pure NiO and Cu-doped... more In this study, the structural, electronic, and thermoelectric properties of pure NiO and Cu-doped NiO were investigated. The structural and optoelectronic properties of nickel oxide and in the supercell containing 32 atoms CuNi15O16 were obtained by density functional theory (DFT) using the generalized gradient approximation (GGA) with the Hubbard correction potential U. The theoretical results obtained using the quantum espresso code show that the ferromagnetic character of the supercell structure is more stable than the antiferromagnetic configuration, and incorporating copper in the NiO matrix reduces the spin-up band structure. The value of the band gap channel is approximately 1.7 eV. The spin-down states cross the Fermi level and indicate the half-metal character of the CuNiO alloys. These results suggest that Cu-doped NiO is a potential candidate for infrared light and spintronic applications. The transport coefficients of the nickel oxide and copper doped NiO were calculated...

physica status solidi (a), 2001

Thin films of indium sulphide containing oxygen have been synthesized following a dry physical pr... more Thin films of indium sulphide containing oxygen have been synthesized following a dry physical process. The constituents are deposited by thermal evaporation on glass substrates and then annealed under argon flow. Polycrystalline bIn 2 S 3 containing oxygen thin films are obtained as soon as the temperature of annealing is between 623 and 723 K. In this paper, these bIn 2 S 3 thin films have optically been studied. The optical band gap is direct. Its value is not dependent on the temperature of annealing. It is about 2.8 eV, which is higher than that of bIn 2 S 3 single crystal. This high value is related to the presence of oxygen in the films. The extinction coefficient k and the refractive index n of the films have also been found independent of the annealing temperature. These optical properties make the films studied good candidates to be substituted to CdS in Cu(In,Ga)Se 2 based solar cells. Cet article est consacré à l'é tude des proprié té s optiques de couches minces de sulfure d'indium (In 2 S 3) ré alisé es par é vaporation thermique sous vide suivie d'un recuit sous flux d'argon. L'influence de la tempé rature de traitement thermique sur le coefficient d'extinction et sur l'indice de ré fraction des couches a é té é tudié e. La largeur de la bande interdite des couches traité es à 623, 673 ou 723 K est de 2,8 eV, mettant en jeu une transition de nature directe. Une bande interdite aussi large, celle du monocristal é tant de 2,0 eV, a dé jà été trouvé e par des auteurs à partir de couches obtenues par des processus chimiques et est lié e à la pré sence d'oxygè ne. Ces proprié té s font de ces films d'excellents candidats à la substitution du CdS comme couche tampon dans les cellules solaires à base de Cu(In,Ga)Se 2 .

Engineering, Technology & Applied Science Research

In this paper, Schottky diodes (SDs) obtained by evaporated thin films of aluminum on pulverized ... more In this paper, Schottky diodes (SDs) obtained by evaporated thin films of aluminum on pulverized p-CuInS2/SnO2:F have been studied using J-V-T characteristics in a temperature range of 200-340K. These characteristics show that aluminum acts as a rectifier metal-semiconductor contact. Characteristic variables of the Al/p-CuInS2/SnO2:F junctions, such as the current density, the serial resistance, the parallel conductance, the Schottky barrier height (SBH), and the ideality factor of the SD were obtained by fitting the J-V-T data using the Lambert function. Data analysis was conducted with the use of MATLAB. Results showed that n is greater than 1, which could be explained by the existence of inhomogeneities due to the grain boundaries in CuInS2. Through this analysis, one can see a good agreement between experimental and modeled data. The study has shown that the main contribution in the current conduction in such heterostructures is the thermionic emission (TE) supported by the reco...

Solar Energy Materials and Solar Cells, 2006

AgInS 2 thin films have been prepared on glass substrates by the spray pyrolysis process using an... more AgInS 2 thin films have been prepared on glass substrates by the spray pyrolysis process using an aqueous solution which contains silver acetate (AgCH 3 CO 2), thiourea (SC(NH 2) 2) and indium chloride (InCl 3) as precursors. The depositions were carried out in the range of the substrate temperature from 260 to 420 1C. The value of the concentration ratio in the spray solution of indium and silver elements x ¼ [Ag + ]/[In 3+ ] was varied from 1 to 1.5 with [In 3+ ] ¼ 10 À2 M and [S 2À ]/[In 3+ ] was taken constant, equal to 4. The structural study shows that AgInS 2 thin film, prepared at 420 1C using optimal concentration ratio x ¼ 1:3 crystallizes in the chalcopyrite phase with a strong (1 1 2) X-ray diffraction line. Moreover, microprobe analysis (EPMA) shows that a nearly stoichiometric composition is obtained for these experimental conditions. Indeed, the atomic percentage of elements were. 24.5, 25.0, 49.5 for Ag, In and S, respectively. On the other hand from transmission and reflectance spectra, the obtained band gap energy is 1.83 eV for such film.

Des couches minces de quinizarin (1. 4 dhaq) et d'anthraflavic (2. 6 dhaq) ont ete deposees s... more Des couches minces de quinizarin (1. 4 dhaq) et d'anthraflavic (2. 6 dhaq) ont ete deposees sous vide. Les etudes par absorption infra rouge, diffusion raman, resonance magnetique nucleaire, spectroscopie de photoelectrons (xps) montrent que les dihydroxyanthraquinones (dhaq) ne sont pas decomposes pendant le processus de depot. De plus, les mesures de point de fusion montrent que la purete du film est superieure a celle du produit de depart. On montre que les differences essentielles entre les deux dhaq sont dues au fait que le quinizarin possede une liaison hydrogene contrairement a l'anthraflavic. Plus precisement la bande d'absorption optique de la transition * est situee autour de 2,60 ev dans le quinizarin tandis qu'elle se trouve vers 3,45 ev dans l'anthraflavic. Ceci est attribue a l'effet batochrome de la liaison hydrogene. Apres formation du complexe ag/dhaq on montre que la bande d'absorption du quinizarin situee a 480 nm est modifiee par recui...

Advanced Materials for Optics and Electronics - ADV MATER OPT ELECTRON, 1995

pour,l'Electroni ue, Faculte des Sciences et des Techniques, 2 Rue de la Houssiniere, F-42072 Nan... more pour,l'Electroni ue, Faculte des Sciences et des Techniques, 2 Rue de la Houssiniere, F-42072 Nantes Cedex Quinizarin (1 ,CDHAQ) and As/ I ,4-DHAQ thin films deposited under vacuum were investigated by I-V measurements at various tern ratures. It is shown that when submitted to an electric ohmic. The temperature dependence is I= ex (-A€/kT). The measured activation energy is 0.3eV in the case of pure DHAQ and 30mee in the case of Ag/DHAQ. Therefore we can imagine that in the former case the conductivity is controlled by thermally activated hopping above intermolecular barriers, while in the latter case the conductivity can be attributed to tunnelling between silver grains. field of 5 x lo5 V cm-' or less, the I-G characteristics of AI/DHAQ/AI sandwich structures are

Electrochromic iridium oxide thin films were deposited by spray pyrolysis technique onto indium-d... more Electrochromic iridium oxide thin films were deposited by spray pyrolysis technique onto indium-doped tin oxide (ITO) coated glass substrates using iridium chloride as an aqueous solution. The influence of the substrate temperature, the deposition period of time and the solution molarity have been investigated as related to the film's electrochromic (EC) performance. The electrochromic properties of the films were investigated in a (0.5M H 2 SO 4) aqueous electrolytic solution using cyclic voltammetry (CV). The transmittance has been measured over the spectral wavelength range between 300 and 2400 nm. The substrate temperature (T sub), the deposition period of time, the solution molarity and the colouration and bleaching potentials were optimized and found to be 400 o C, 10 min, 0.02 M, ±0.8 V, respectively. The films have acquired a maximum transmittance solar modulation ΔT s and a maximum visible modulation ΔTv at 630 nm optimal optical modulation. The iridium oxide thin films...

Physica Status Solidi (a), 2004

Zinc sulphide (ZnS) thin films have been prepared on Pyrex substrates by the spray pyrolysis tech... more Zinc sulphide (ZnS) thin films have been prepared on Pyrex substrates by the spray pyrolysis technique using zinc chloride and thiourea as precursors. The depositions were carried out on substrates heated at 450 °C. The films were then annealed under sulphur atmosphere for one hour at 450 or 500 °C. This process allows one to obtain well-crystallized cubic-type -ZnS thin

International Conference on Science and Technology of Synthetic Metals, 1994

Advanced Materials for Optics and Electronics, 1995

Quinizarin (1 ,CDHAQ) and As/ I ,4-DHAQ thin films deposited under vacuum were investigated by I-... more Quinizarin (1 ,CDHAQ) and As/ I ,4-DHAQ thin films deposited under vacuum were investigated by I-V measurements at various tern ratures. It is shown that when submitted to an electric ohmic. The temperature dependence is I= ex (-A€/kT). The measured activation energy is 0.3eV in the case of pure DHAQ and 30mee in the case of Ag/DHAQ. Therefore we can imagine that in the former case the conductivity is controlled by thermally activated hopping above intermolecular barriers, while in the latter case the conductivity can be attributed to tunnelling between silver grains. field of 5 x lo5 V cm-' or less, the I-G characteristics of AI/DHAQ/AI sandwich structures are

International Journal of Applied Physics and Mathematics, 2013

Electrochromic iridium oxide thin films were deposited by spray pyrolysis technique onto indium-d... more Electrochromic iridium oxide thin films were deposited by spray pyrolysis technique onto indium-doped tin oxide (ITO) coated glass substrates using iridium chloride as an aqueous solution. The influence of the substrate temperature, the deposition period of time and the solution molarity have been investigated as related to the film's electrochromic (EC) performance. The electrochromic properties of the films were investigated in a (0.5M H 2 SO 4 ) aqueous electrolytic solution using cyclic voltammetry (CV). The transmittance has been measured over the spectral wavelength range between 300 and 2400 nm. The substrate temperature (T sub ), the deposition period of time, the solution molarity and the colouration and bleaching potentials were optimized and found to be 400 o C, 10 min, 0.02 M, ±0.8 V, respectively. The films have acquired a maximum transmittance solar modulation ΔT s and a maximum visible modulation ΔTv at 630 nm optimal optical modulation. The iridium oxide thin films have demonstrated a pronounced anodic electrochromic behavior owing to Ir +4 Ir +3 intervalance charge transitions.

Synthetic Metals, 2005

Ag 2 S thin films have been prepared on glass substrates by the sequential thermal evaporation te... more Ag 2 S thin films have been prepared on glass substrates by the sequential thermal evaporation technique. X-ray diffraction analysis shows that the films annealed at Ta = 250 • C in argon atmosphere are well crystallised in the ␤-Ag 2 S phase with crystallinity preferentially oriented towards (1 0 3) direction. Microprobe analysis shows that a nearly stoichiometric composition is obtained under such annealing temperature. The optical properties of the films are investigated using spectrophotometric measurements of transmittance T(λ) and reflectance R(λ) in the wavelength range 500-2000 nm. The refractive and absorption indexes, n and k, of Ag 2 S thin films are calculated from the values of the measured transmittance and reflectance. The study of the absorption coefficient of these films versus incident energy revealed that the value of the band gap energy is of the order of 1.1 eV. For the first time, a photovoltaic effect is reported using Ag 2 S as absorber.

Thin Solid Films, 2001

CuInS thin films have been deposited by spray pyrolysis. X-Ray diffraction spectra show that a su... more CuInS thin films have been deposited by spray pyrolysis. X-Ray diffraction spectra show that a substrate temperature T G 590 2 s w x w x K with a ratio of the concentration in the pulverized solution of Cu r In s 1.1 permits well crystallized thin films with a Ž . preferential orientation along the 112 direction to be obtained. Scanning electron micrographs of the cross-sectional and top views of the surface show evidence of the good homogeneity of the films. Microprobe analysis as well as X-ray photoelectron spectroscopy show that an almost stoichiometric composition is obtained. In the best films only 3᎐8 at.% of oxygen is present, which is very promising for such a simple growth technique. Moreover, the oxygen present in the films segregates at the grain boundaries since there is not any significant variation of the interplanar spacing and the optical band gap with the presence of Ž . oxygen. The optical band gap values 1.45 eV increases slightly with the crystalline state. ᮊ

Solar Energy Materials and Solar Cells, 2006

AgInS 2 thin films have been prepared on glass substrates by the spray pyrolysis process using an... more AgInS 2 thin films have been prepared on glass substrates by the spray pyrolysis process using an aqueous solution which contains silver acetate (AgCH 3 CO 2 ), thiourea (SC(NH 2 ) 2 ) and indium chloride (InCl 3 ) as precursors. The depositions were carried out in the range of the substrate temperature from 260 to 420 1C. The value of the concentration ratio in the spray solution of indium and silver elements x ¼ [Ag + ]/[In 3+ ] was varied from 1 to 1.5 with [In 3+ ] ¼ 10 À2 M and [S 2À ]/[In 3+ ] was taken constant, equal to 4. The structural study shows that AgInS 2 thin film, prepared at 420 1C using optimal concentration ratio x ¼ 1:3 crystallizes in the chalcopyrite phase with a strong (1 1 2) X-ray diffraction line. Moreover, microprobe analysis (EPMA) shows that a nearly stoichiometric composition is obtained for these experimental conditions. Indeed, the atomic percentage of elements were. 24.5, 25.0, 49.5 for Ag, In and S, respectively. On the other hand from transmission and reflectance spectra, the obtained band gap energy is 1.83 eV for such film. r

Solar Energy Materials and Solar Cells, 2007

AgInS 2 thin films have been prepared on glass substrates by the spray pyrolysis process using an... more AgInS 2 thin films have been prepared on glass substrates by the spray pyrolysis process using an aqueous solution, containing silver acetate (AgCH 3 CO 2 ), thiourea (SC(NH 2 ) 2 ) and indium chloride (InCl 3 ) as precursors. The depositions were carried out at the substrate temperature of 420 1C. The value of the concentration ratio in the spray solution of indium and silver elements x ¼ [Ag + ]/[In 3+ ] was equal to 1.3, whereas y ¼ [S 2À ]/[In 3+ ] varied between 4 and 7. The structural study (XRD, EPMA and AFM ) shows that all films obtained using y ¼ 4 with a nearly stoichiometric composition consist essentially of AgInS 2 chalcopyrite compound and they exhibit in the as-deposited state, the best crystallinity with a (1 1 2) preferential orientation. On the other hand, films obtained using y higher than y ¼ 4 exhibit p-type character. Moreover, the optical analysis via the transmittance, reflectance reveals that the band-gap energy E g increases slightly as a function of y composition (E g varies from 1.87 to 2.07 eV).

physica status solidi (a), 2004

Materials Chemistry and Physics, 1995

(l-CAQ) thin films deposited under vacuum were investigated by IR absorption, nuclear magnetic re... more (l-CAQ) thin films deposited under vacuum were investigated by IR absorption, nuclear magnetic resonance, X-ray diffraction and electron spectroscopy for chemical analysis. It was found that l-CAQ did not decompose during the deposition process. The measurement of the melting point shows that the vacuum deposition process increases the purity of the I-CAQ. The first optical absorption band, situated around 370 nm, is attributed to the r-+r* transition. After the realization of a Ag/l-CAQ complex, there is a small bathochromic shift of this absorption band. This effect may be attributed to the modification of the r electron distribution of the molecule.

Journal of Physics and Chemistry of Solids, 1995

ABSTRACT We have deposited under vacuum two dihydroxyanthraquinones (DHAQ); quinizarin (1,4-DHAQ)... more ABSTRACT We have deposited under vacuum two dihydroxyanthraquinones (DHAQ); quinizarin (1,4-DHAQ) and anthraflavic (2,6-DHAQ). The former exhibits a strong absorption band in the visible range at about 480 nm which is attributed to a π → π∗ transition. The low value of the energy is attributed to the red shift effect of the hydrogen bond. For the latter compound this same π → π∗ absorbs at 360 nm because there is no hydrogen bond in 2,6-DHAQ. The films, after deposition, were characterized by infrared (IR), visible absorption and nuclear magnetic resonance (NMR) in order to check that the products did not decompose during the deposition process. In the case of 1,4-DHAQ the IR spectra of a thin film of quinizarin (tQ < 3 μm) and a thick film (tQ > 5 μm) were different. Only the spectra of thick films were identical to the reference powder spectra. This difference can be attributed to the high degree of disorder in the thin films. The optical properties of silver/DHAQ superposed films were studied using their thermal history as a parameter. The properties of Ag/2,6-DHAQ thin film samples, before or after annealing, were not modified, while those of 1,4-DHAQ thin films were modified after annealing of Ag/1,4-DHAQ samples.

Journal of Alloys and Compounds, 2009

The ternary compound CuInS 2 is attractive for solar cells due to its band gap of 1.54 eV which b... more The ternary compound CuInS 2 is attractive for solar cells due to its band gap of 1.54 eV which borders the optimum value necessary for conversion of a solar spectrum. Recently, works on thin film cells based on this material (ZnO/CuInS 2 ) has been reported to show efficiency as high as 11.4%.

Physica Scripta

physica status solidi (a), 2001

Engineering, Technology & Applied Science Research

Solar Energy Materials and Solar Cells, 2006

Advanced Materials for Optics and Electronics - ADV MATER OPT ELECTRON, 1995

Physica Status Solidi (a), 2004

International Conference on Science and Technology of Synthetic Metals, 1994

Advanced Materials for Optics and Electronics, 1995

International Journal of Applied Physics and Mathematics, 2013

Electrochromic iridium oxide thin films were deposited by spray pyrolysis technique onto indium-d... more Electrochromic iridium oxide thin films were deposited by spray pyrolysis technique onto indium-doped tin oxide (ITO) coated glass substrates using iridium chloride as an aqueous solution. The influence of the substrate temperature, the deposition period of time and the solution molarity have been investigated as related to the film's electrochromic (EC) performance. The electrochromic properties of the films were investigated in a (0.5M H 2 SO 4 ) aqueous electrolytic solution using cyclic voltammetry (CV). The transmittance has been measured over the spectral wavelength range between 300 and 2400 nm. The substrate temperature (T sub ), the deposition period of time, the solution molarity and the colouration and bleaching potentials were optimized and found to be 400 o C, 10 min, 0.02 M, ±0.8 V, respectively. The films have acquired a maximum transmittance solar modulation ΔT s and a maximum visible modulation ΔTv at 630 nm optimal optical modulation. The iridium oxide thin films have demonstrated a pronounced anodic electrochromic behavior owing to Ir +4 Ir +3 intervalance charge transitions.

Synthetic Metals, 2005

Thin Solid Films, 2001

Solar Energy Materials and Solar Cells, 2006

AgInS 2 thin films have been prepared on glass substrates by the spray pyrolysis process using an... more AgInS 2 thin films have been prepared on glass substrates by the spray pyrolysis process using an aqueous solution which contains silver acetate (AgCH 3 CO 2 ), thiourea (SC(NH 2 ) 2 ) and indium chloride (InCl 3 ) as precursors. The depositions were carried out in the range of the substrate temperature from 260 to 420 1C. The value of the concentration ratio in the spray solution of indium and silver elements x ¼ [Ag + ]/[In 3+ ] was varied from 1 to 1.5 with [In 3+ ] ¼ 10 À2 M and [S 2À ]/[In 3+ ] was taken constant, equal to 4. The structural study shows that AgInS 2 thin film, prepared at 420 1C using optimal concentration ratio x ¼ 1:3 crystallizes in the chalcopyrite phase with a strong (1 1 2) X-ray diffraction line. Moreover, microprobe analysis (EPMA) shows that a nearly stoichiometric composition is obtained for these experimental conditions. Indeed, the atomic percentage of elements were. 24.5, 25.0, 49.5 for Ag, In and S, respectively. On the other hand from transmission and reflectance spectra, the obtained band gap energy is 1.83 eV for such film. r

Solar Energy Materials and Solar Cells, 2007

AgInS 2 thin films have been prepared on glass substrates by the spray pyrolysis process using an... more AgInS 2 thin films have been prepared on glass substrates by the spray pyrolysis process using an aqueous solution, containing silver acetate (AgCH 3 CO 2 ), thiourea (SC(NH 2 ) 2 ) and indium chloride (InCl 3 ) as precursors. The depositions were carried out at the substrate temperature of 420 1C. The value of the concentration ratio in the spray solution of indium and silver elements x ¼ [Ag + ]/[In 3+ ] was equal to 1.3, whereas y ¼ [S 2À ]/[In 3+ ] varied between 4 and 7. The structural study (XRD, EPMA and AFM ) shows that all films obtained using y ¼ 4 with a nearly stoichiometric composition consist essentially of AgInS 2 chalcopyrite compound and they exhibit in the as-deposited state, the best crystallinity with a (1 1 2) preferential orientation. On the other hand, films obtained using y higher than y ¼ 4 exhibit p-type character. Moreover, the optical analysis via the transmittance, reflectance reveals that the band-gap energy E g increases slightly as a function of y composition (E g varies from 1.87 to 2.07 eV).

physica status solidi (a), 2004

Materials Chemistry and Physics, 1995

Journal of Physics and Chemistry of Solids, 1995

Journal of Alloys and Compounds, 2009