F. Saadallah | IPEIN - Academia.edu (original) (raw)

Papers by F. Saadallah

Journal of Materials Science: Materials in Electronics, 2021

In this paper, Ni was used as a doping element for La2O3 thin films using the spray pyrolysis met... more In this paper, Ni was used as a doping element for La2O3 thin films using the spray pyrolysis method. First, the structural properties of obtained films were investigated by means of X-ray diffraction technique and Raman Spectroscopy. Furthermore, the morphological properties were examined by the scanning electron microscopy. Second, the optical properties of these films were examined using the photoluminescence measurements. Moreover, the electrical properties of Ni-doped La2O3 thin films are discussed. Finally, the photocatalytic effects were investigated by controlling the degradation of the both pollutants: methylene blue and methylene orange under sunlight. The La2O3 thin film-doped with Ni could enhance the photocatalysts properties of the film for wastewater treatment under sunlight since a cost-effective chemical process was used to prepare such doped films.

Optik, 2021

Abstract Co doped La2O3 thin films are prepared successfully by the spray pyrolysis method. These... more Abstract Co doped La2O3 thin films are prepared successfully by the spray pyrolysis method. These thin layers are characterized by different techniques. First, the structural and the morphological properties are studied by XRD, Raman and SEM techniques. Second, the photoluminescences (PL) measurements are carried out on these films and tested for the photocatalysis of methyl orange dye. La2O3 thin film at Co content of 5% exhibits the best photocatalytic activity. Finally, Co doped layers are used as antibacterial agents against two strains Pseudomonas Aeroginosa and Staphylococcus aureus. We notice that pure La2O3, La2O3: Co (1%) and La2O3:Co (5%) have stopped the bacterial growth which revealed a residual viability 100% against Pseudomonas Aeroginosa. Besides, the best antibacterial activity against Staphylococcus aureus is rather obtained with La2O3: Co (5%).

Optik, 2021

Abstract This work contains the protocol of the preparation of LaNiO3/La2O3 composites using the ... more Abstract This work contains the protocol of the preparation of LaNiO3/La2O3 composites using the spray pyrolysis method. First, the structural properties are investigated by X-ray diffraction (XRD) as well as by scanning electron microscopy showing the existence of both LaNiO3 and La2O3 varieties. Also, Raman and Fourier-transform infrared spectroscopies (FTIR) depict the presence of these two materials. Second, the reflectance and the transmittance of the different samples are studied and the optical band gap value varies from 1.62 to 2.27 eV. Furthermore, the evaluation of the PL measurements describes the peaks in the emission ranges of violet, blue and green. Finally, the thermal properties of this studied composite is done via EPE technique reveals that the composite deposited on ITO substrates heat more than when it deposited at glass.

Journal of Materials Science: Materials in Electronics, 2020

This paper deals with the synthesis of Cu/La 2 O 3 thin layers and the effect of their surface de... more This paper deals with the synthesis of Cu/La 2 O 3 thin layers and the effect of their surface defects in the photocatalysis process. First, La 2 O 3 thin layers were obtained using pyrolysis technique by spraying at 460 °C on glass substrates. Then, 10 nm thick of Cu is deposited on the top of La 2 O 3 layers by the thermal evaporation process. Finally, these layers are subjected to a heat treatment under air. In order to identify their structures and morphological properties, these layers were characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscope. The optical and electrical properties of these layers were examined using photoluminescence and conductivity measurements, respectively. In addition, the photocatalytic activities of La 2 O 3 :Cu thin films were studied by monitoring the degradation of aqueous methylene blue under solar irradiation. It was found that the layer annealed for 2 h exhibited the highest photocatalytic activity. This fact can be explained by the enhancement of its structural and morphological properties.

Materials Research Express, 2019

Silicon, 2018

We have elaborated nanocomposites based Porous silicon (PS) and rhodamine 6G (Rh 6G) by simple im... more We have elaborated nanocomposites based Porous silicon (PS) and rhodamine 6G (Rh 6G) by simple impregnation. New luminescence properties were shown. This luminescence could occur by energy transfer from silicon nanocristallites to dye molecules. FTIR spectroscopy suggests the incorporation of rhodamine molecules into the pores of the matrices. An energy transfer was demonstrated from Si nanocrystallites to Rh6G molecules. We also study the effect of the concentration of Rh6G molecule on optical properties of nanocomposites PS/Rh6G.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2017

Metal transition doped oxide thin films or nanocomposites have recently emerged at the forefront ... more Metal transition doped oxide thin films or nanocomposites have recently emerged at the forefront of potentials research. With the focus mainly on efficiency, the aspect of stability against optical irradiation of such materials has so far not been thoroughly addressed. This work covers the synthesis of silver doped Lanthanum oxide thin films (La 2 O 3 :Ag) which have been prepared by the spray pyrolysis technique on glass substrates at 460°C. Then, Ag thin films were grown on Lanthanum oxide thin films by thermal evaporation. The present work aims to reach the synthesis of La 2 O 3 :Ag thin films using both the spray pyrolysis and thermal evaporation techniques. First, X-ray diffraction analysis shows that undoped and Ag doped films crystallize in a mixture of hexagonal and cubic phase with crystallites oriented along (001) direction. Raman spectroscopy shows the bands positions corresponding to hexagonal and cubic phases. On the other hand, an attempt regarding their optical properties has been carried out by means of photoluminescence measurements. Second, from electrical conductivity measurements, the activation energy decreases from 1.42 to 1.09 eV with the increase of annealing time and the charge carriers are following the CBH model as dominant

International Journal of Photoenergy, 2011

Photothermal deflection spectroscopy (PDS) is carried out in order to investigate thermal and opt... more Photothermal deflection spectroscopy (PDS) is carried out in order to investigate thermal and optical properties of Al doped In2S3. The influence of thermal annealing on its gap energy as well as its thermal properties is revealed. In this way, we notice that thermal conductivity is increased and the gap energy is reduced. These features are probably due to the improvement of the crystalline structure of the sample.

American Journal of Condensed Matter Physics, 2012

Photothermal deflection PTD is used in order to reveal the influence of Te doping on non radiativ... more Photothermal deflection PTD is used in order to reveal the influence of Te doping on non radiative carrier lifetime for GaSb bulk sample when illuminated by a modulated and monochromatic light beam. Theoretical simulations are obtained from an adapted theoretical model, based on the resolution of both heat and carrier diffusion equations. Auger recombination coefficient obtained from the linear relation between lifetime and the inverse of squared concentration is in agreement with literature. Moreover, it is found that low n-doping reduces the surface recombination velocity S because of dangling bonds neutralisation at the surface. However for higher doping concentration, S is enhanced by Te doping.

Physica B: Condensed Matter, 2007

ABSTRACT The knowledge of doping effects on optical and thermal properties of semiconductors is c... more ABSTRACT The knowledge of doping effects on optical and thermal properties of semiconductors is crucial for the development of opto-electronic compounds. The purpose of this work is to investigate these effects by mirage effect technique and spectroscopic ellipsometry SE.The near gap optical spectra are obtained from photothermal signal for differently doped Si and GaAs bulk samples. However, the above bandgap absorption is determined from SE. These spectra show that absorption in the near IR increases with dopant density and also the bandgap shifts toward low energies. This behavior is due to free carrier absorption which could be obtained by subtracting phonon-assisted absorption from the measured spectrum. This carrier absorption is related to the dopant density through a semi-empirical model.We have also used the photothermal signal phase to measure the influence of doping on thermal diffusivity.

Optik - International Journal for Light and Electron Optics, 2013

Photothermal deflection spectroscopy is used to investigate thermal and optical properties of MOV... more Photothermal deflection spectroscopy is used to investigate thermal and optical properties of MOVPE grown GaN thin layers deposited on sapphire substrate. The effects of Si doping on absorption spectrum and gap energy are revealed. Also, doping-induced free carrier absorption is extracted from absorption in the sub-gap region. Moreover, the variations of photothermal signal versus modulation frequency are used to determine thermal properties of these films. The measured thermal conductivity is clearly decreased by Si doping, the main reason should be the phonon scattering on point defects.

Journal of Alloys and Compounds, 2009

GaSb is a direct gap semiconductor (0.72 ev) having good carriers motility and significant electr... more GaSb is a direct gap semiconductor (0.72 ev) having good carriers motility and significant electro-optical potential in the near IR range. As substrate or active layer, GaSb can be employed in conjunction with many semiconductors such as (AlGa)Sb or In(AsSb) and has interesting hetero junction potential for detectors, lasers and quantum well structures. The aim of this work is to investigate the influence of doping on the opto-thermal properties (optical absorption, refractive index and thermal diffusivity) of doped and undoped GaSb bulk throw, the phothermal deflection and spectroscopic reflectivity. It is found that absorption below the gap and thermal diffusivity increases with doping concentration.

Applied Physics A, 2013

Photothermal deflection spectroscopy is used in order to investigate near-and sub-band gap absorp... more Photothermal deflection spectroscopy is used in order to investigate near-and sub-band gap absorption of Si-doped GaSb epilayers deposited by MBE on a semiinsulating GaAs substrate. The optical absorption spectra show an extra absorption on the transparency region below the bandgap due to free-carrier absorption. However, for energies above the gap, we notice a linear behavior of the square root of the absorption coefficient versus the heating beam energy, which is attributed to phonon-assisted absorption. From interpolation of the phonon absorption to low energies we have determined the free-carrier absorption that is found to follow the Drude law.

Applied Optics, 2002

ABSTRACT We present the study of thermal and optical properties of 15.5 pair of GaAlAsSb/AlAsSb l... more ABSTRACT We present the study of thermal and optical properties of 15.5 pair of GaAlAsSb/AlAsSb layers deposited upon a GaSb substrate by photothermal deflection spectroscopy. This stacking of layers constitutes a distributed Bragg mirror.

Applied Physics A, 2013

ZnO thin films were grown by metal-organic chemical vapor deposition on Zn-and O-polar surfaces o... more ZnO thin films were grown by metal-organic chemical vapor deposition on Zn-and O-polar surfaces of ZnO substrate. The effect of Zn-and O-polar substrate on the surface morphology and opto-thermal proprieties has been studied. Hall-measurements were used to determine the carrier concentration of the deposited films. Photothermal deflection spectroscopy (PDS) was used to determine the optical absorption spectrum and the gap energy by comparing experimental amplitude of the photothermal signal to the corresponding theoretical one. Thermal conductivity and diffusivity were also deduced from the photothermal deflection measurements. The found values were very low due to the thermal resistivity of the layer-substrate interface.

In this work, β-SnS 2 thin films have been prepared on glass substrates by the spray pyrolysis te... more In this work, β-SnS 2 thin films have been prepared on glass substrates by the spray pyrolysis technique using an alcohol solution which contains tin chloride (SnCl 4 ) and thiourea (SC(NH 2 ) 2 ) as precursors. The structural study shows that β-SnS 2 thin film prepared using optimal experimental conditions: substrate temperature T s = 280 °C and the concentration ratio of sulfur and tin elements in the spray solution x = [S]/[Sn] = 2.5, crystallizes in the hexagonal phase with a strong (001) X-ray diffraction line. In the same way, microprobe analysis (EPMA) as well as X-ray photoelectron spectroscopy (XPS) show the presence of undiserable phase of SnO 2 . From the transmission and reflectance spectra, the band gap energy is 2.65 eV. On the other hand, the photothermal properties of such films have been studied. Indeed, the analysis of β-SnS 2 thin films via the photodeflection spectroscopy including the effect of the inhomogeneity at the surface (roughness) and in the bulk (air in...

Materials Science and Engineering: A, 2010

Mechanical property measurements, positron annihilation lifetime (PAL) measurements and metallogr... more Mechanical property measurements, positron annihilation lifetime (PAL) measurements and metallographic observations, have been performed to study the isochronal annealing of commercial pure Cu in the temperature range from 25 up to 850 • C. A positive correlation has been found between positron lifetime ( ) and both the tensile strain ( L/L 0 ) and Vicker's microhardness (H v ). This correlation shows the presence of three annealing stages in commercial pure Cu which are attributed to recovery, recrystallization, and grain growth. These different stages were studied by both pure tensile and combined torsion-tension deformation for samples pre-annealed at the different annealing stages. Plastic instability behavior is observed in the case of combined torsion-tension deformation. It is observed that the onset and disappearance of this instability depend on some parameters such as mode of deformation, applied axial tensile stress and pre-annealing temperature.

International Journal of Photoenergy, 2012

... View at Publisher · View at Google Scholar · View at Scopus; M. Ghrib, M. Gaidi, T. Ghrib, N.... more ... View at Publisher · View at Google Scholar · View at Scopus; M. Ghrib, M. Gaidi, T. Ghrib, N. Khedher, M. Ben Salam, and H. Ezzaouia, “Morphological and optical properties changes in nanocrystalline Si (nc-Si) deposited on porous aluminum nanostructures by plasma ...

Journal of Magnetism and Magnetic Materials, 2015

ABSTRACT NiMn2O4 ternary nickel manganese oxide thin films spinels have been grown on glass subst... more ABSTRACT NiMn2O4 ternary nickel manganese oxide thin films spinels have been grown on glass substrates at 350 °C through spray pyrolysis technique. X-ray diffraction and Raman spectroscopy analyses show that the synthesized film has mainly cubic spinel structure with a preferred orientation along (111) plane. Some optical constants such as the refractive index (n), extinction coefficient (k), Urbach energy (EU=342 eV) and optical energy band gap (Eg=1.07 eV) have been calculated from reflection-transmission spectra. The mirage effect technique has been used to estimate the thermal conductivity (Kc). Its value is Kc=25 W m−1 K−1. The real part of the ac the conductivity behaviour has been investigated in the frequency range 100 Hz to 1 MHz. It was found that the real conductivity follows a power law (Aωs). The dc conductivity has been studied in the temperature range from 250 °C to 375 °C and supports the variable range hopping model proposed by Mott. The activation energy value estimated from the relaxation frequency is Ea~0.32 eV. Moreover, the temperature dependency of the resistance indicates that conduction was well described by a variable range hopping model, in which electron transfer takes place between Mn3+ and Mn4+ ions.

Physics Procedia, 2009

ABSTRACT The aim of this work is to investigate the influence of Si-doping on the optical, therma... more ABSTRACT The aim of this work is to investigate the influence of Si-doping on the optical, thermal and electrical properties of GaSb epitaxial layers. Such an influence was quantified through photoluminescence (PL), mirage effect (photothermal spectroscopy) and Hall effect measurements. Several GaSb samples, grown by Molecular Beam Epitaxy (MBE) on (100)-oriented GaAs semiinsulating substrates, with different Si-doping levels ranging from up to were tested. As a comparison, the same measurements were also performed on a GaSb non intentionally doped layer. The Hall effect data shows a monotonic decrease in carrier mobility when the hole concentration increase.The effect of band-to-band, band-impurity transitions on the PL gap E0 and the influence of high impurity concentration on the PL and absorption spectra have been also studied. Finally, the optical absorption changes induced by Si-doping on GaSb samples were investigated by photothermal deflection. It was shown that this technique allows a very precise deduction of the real interband gap energy of a semiconductor material as GaSb.Thermal conductivities were also deduced from the photothermal deflection measurements. The found values are very low due to the thermal resistivity of the layer-substrate interface but also due to the lattice-mismatch between GaSb epilayers and the GaAs substrate. However, the contribution of the free carriers to the thermal conductivity, with a high p-doping level (), could be highlighted.

Journal of Materials Science: Materials in Electronics, 2021

In this paper, Ni was used as a doping element for La2O3 thin films using the spray pyrolysis met... more In this paper, Ni was used as a doping element for La2O3 thin films using the spray pyrolysis method. First, the structural properties of obtained films were investigated by means of X-ray diffraction technique and Raman Spectroscopy. Furthermore, the morphological properties were examined by the scanning electron microscopy. Second, the optical properties of these films were examined using the photoluminescence measurements. Moreover, the electrical properties of Ni-doped La2O3 thin films are discussed. Finally, the photocatalytic effects were investigated by controlling the degradation of the both pollutants: methylene blue and methylene orange under sunlight. The La2O3 thin film-doped with Ni could enhance the photocatalysts properties of the film for wastewater treatment under sunlight since a cost-effective chemical process was used to prepare such doped films.

Optik, 2021

Abstract Co doped La2O3 thin films are prepared successfully by the spray pyrolysis method. These... more Abstract Co doped La2O3 thin films are prepared successfully by the spray pyrolysis method. These thin layers are characterized by different techniques. First, the structural and the morphological properties are studied by XRD, Raman and SEM techniques. Second, the photoluminescences (PL) measurements are carried out on these films and tested for the photocatalysis of methyl orange dye. La2O3 thin film at Co content of 5% exhibits the best photocatalytic activity. Finally, Co doped layers are used as antibacterial agents against two strains Pseudomonas Aeroginosa and Staphylococcus aureus. We notice that pure La2O3, La2O3: Co (1%) and La2O3:Co (5%) have stopped the bacterial growth which revealed a residual viability 100% against Pseudomonas Aeroginosa. Besides, the best antibacterial activity against Staphylococcus aureus is rather obtained with La2O3: Co (5%).

Optik, 2021

Abstract This work contains the protocol of the preparation of LaNiO3/La2O3 composites using the ... more Abstract This work contains the protocol of the preparation of LaNiO3/La2O3 composites using the spray pyrolysis method. First, the structural properties are investigated by X-ray diffraction (XRD) as well as by scanning electron microscopy showing the existence of both LaNiO3 and La2O3 varieties. Also, Raman and Fourier-transform infrared spectroscopies (FTIR) depict the presence of these two materials. Second, the reflectance and the transmittance of the different samples are studied and the optical band gap value varies from 1.62 to 2.27 eV. Furthermore, the evaluation of the PL measurements describes the peaks in the emission ranges of violet, blue and green. Finally, the thermal properties of this studied composite is done via EPE technique reveals that the composite deposited on ITO substrates heat more than when it deposited at glass.

Journal of Materials Science: Materials in Electronics, 2020

This paper deals with the synthesis of Cu/La 2 O 3 thin layers and the effect of their surface de... more This paper deals with the synthesis of Cu/La 2 O 3 thin layers and the effect of their surface defects in the photocatalysis process. First, La 2 O 3 thin layers were obtained using pyrolysis technique by spraying at 460 °C on glass substrates. Then, 10 nm thick of Cu is deposited on the top of La 2 O 3 layers by the thermal evaporation process. Finally, these layers are subjected to a heat treatment under air. In order to identify their structures and morphological properties, these layers were characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscope. The optical and electrical properties of these layers were examined using photoluminescence and conductivity measurements, respectively. In addition, the photocatalytic activities of La 2 O 3 :Cu thin films were studied by monitoring the degradation of aqueous methylene blue under solar irradiation. It was found that the layer annealed for 2 h exhibited the highest photocatalytic activity. This fact can be explained by the enhancement of its structural and morphological properties.

Materials Research Express, 2019

Silicon, 2018

We have elaborated nanocomposites based Porous silicon (PS) and rhodamine 6G (Rh 6G) by simple im... more We have elaborated nanocomposites based Porous silicon (PS) and rhodamine 6G (Rh 6G) by simple impregnation. New luminescence properties were shown. This luminescence could occur by energy transfer from silicon nanocristallites to dye molecules. FTIR spectroscopy suggests the incorporation of rhodamine molecules into the pores of the matrices. An energy transfer was demonstrated from Si nanocrystallites to Rh6G molecules. We also study the effect of the concentration of Rh6G molecule on optical properties of nanocomposites PS/Rh6G.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2017

Metal transition doped oxide thin films or nanocomposites have recently emerged at the forefront ... more Metal transition doped oxide thin films or nanocomposites have recently emerged at the forefront of potentials research. With the focus mainly on efficiency, the aspect of stability against optical irradiation of such materials has so far not been thoroughly addressed. This work covers the synthesis of silver doped Lanthanum oxide thin films (La 2 O 3 :Ag) which have been prepared by the spray pyrolysis technique on glass substrates at 460°C. Then, Ag thin films were grown on Lanthanum oxide thin films by thermal evaporation. The present work aims to reach the synthesis of La 2 O 3 :Ag thin films using both the spray pyrolysis and thermal evaporation techniques. First, X-ray diffraction analysis shows that undoped and Ag doped films crystallize in a mixture of hexagonal and cubic phase with crystallites oriented along (001) direction. Raman spectroscopy shows the bands positions corresponding to hexagonal and cubic phases. On the other hand, an attempt regarding their optical properties has been carried out by means of photoluminescence measurements. Second, from electrical conductivity measurements, the activation energy decreases from 1.42 to 1.09 eV with the increase of annealing time and the charge carriers are following the CBH model as dominant

International Journal of Photoenergy, 2011

Photothermal deflection spectroscopy (PDS) is carried out in order to investigate thermal and opt... more Photothermal deflection spectroscopy (PDS) is carried out in order to investigate thermal and optical properties of Al doped In2S3. The influence of thermal annealing on its gap energy as well as its thermal properties is revealed. In this way, we notice that thermal conductivity is increased and the gap energy is reduced. These features are probably due to the improvement of the crystalline structure of the sample.

American Journal of Condensed Matter Physics, 2012

Photothermal deflection PTD is used in order to reveal the influence of Te doping on non radiativ... more Photothermal deflection PTD is used in order to reveal the influence of Te doping on non radiative carrier lifetime for GaSb bulk sample when illuminated by a modulated and monochromatic light beam. Theoretical simulations are obtained from an adapted theoretical model, based on the resolution of both heat and carrier diffusion equations. Auger recombination coefficient obtained from the linear relation between lifetime and the inverse of squared concentration is in agreement with literature. Moreover, it is found that low n-doping reduces the surface recombination velocity S because of dangling bonds neutralisation at the surface. However for higher doping concentration, S is enhanced by Te doping.

Physica B: Condensed Matter, 2007

ABSTRACT The knowledge of doping effects on optical and thermal properties of semiconductors is c... more ABSTRACT The knowledge of doping effects on optical and thermal properties of semiconductors is crucial for the development of opto-electronic compounds. The purpose of this work is to investigate these effects by mirage effect technique and spectroscopic ellipsometry SE.The near gap optical spectra are obtained from photothermal signal for differently doped Si and GaAs bulk samples. However, the above bandgap absorption is determined from SE. These spectra show that absorption in the near IR increases with dopant density and also the bandgap shifts toward low energies. This behavior is due to free carrier absorption which could be obtained by subtracting phonon-assisted absorption from the measured spectrum. This carrier absorption is related to the dopant density through a semi-empirical model.We have also used the photothermal signal phase to measure the influence of doping on thermal diffusivity.

Optik - International Journal for Light and Electron Optics, 2013

Photothermal deflection spectroscopy is used to investigate thermal and optical properties of MOV... more Photothermal deflection spectroscopy is used to investigate thermal and optical properties of MOVPE grown GaN thin layers deposited on sapphire substrate. The effects of Si doping on absorption spectrum and gap energy are revealed. Also, doping-induced free carrier absorption is extracted from absorption in the sub-gap region. Moreover, the variations of photothermal signal versus modulation frequency are used to determine thermal properties of these films. The measured thermal conductivity is clearly decreased by Si doping, the main reason should be the phonon scattering on point defects.

Journal of Alloys and Compounds, 2009

GaSb is a direct gap semiconductor (0.72 ev) having good carriers motility and significant electr... more GaSb is a direct gap semiconductor (0.72 ev) having good carriers motility and significant electro-optical potential in the near IR range. As substrate or active layer, GaSb can be employed in conjunction with many semiconductors such as (AlGa)Sb or In(AsSb) and has interesting hetero junction potential for detectors, lasers and quantum well structures. The aim of this work is to investigate the influence of doping on the opto-thermal properties (optical absorption, refractive index and thermal diffusivity) of doped and undoped GaSb bulk throw, the phothermal deflection and spectroscopic reflectivity. It is found that absorption below the gap and thermal diffusivity increases with doping concentration.

Applied Physics A, 2013

Photothermal deflection spectroscopy is used in order to investigate near-and sub-band gap absorp... more Photothermal deflection spectroscopy is used in order to investigate near-and sub-band gap absorption of Si-doped GaSb epilayers deposited by MBE on a semiinsulating GaAs substrate. The optical absorption spectra show an extra absorption on the transparency region below the bandgap due to free-carrier absorption. However, for energies above the gap, we notice a linear behavior of the square root of the absorption coefficient versus the heating beam energy, which is attributed to phonon-assisted absorption. From interpolation of the phonon absorption to low energies we have determined the free-carrier absorption that is found to follow the Drude law.

Applied Optics, 2002

ABSTRACT We present the study of thermal and optical properties of 15.5 pair of GaAlAsSb/AlAsSb l... more ABSTRACT We present the study of thermal and optical properties of 15.5 pair of GaAlAsSb/AlAsSb layers deposited upon a GaSb substrate by photothermal deflection spectroscopy. This stacking of layers constitutes a distributed Bragg mirror.

Applied Physics A, 2013

ZnO thin films were grown by metal-organic chemical vapor deposition on Zn-and O-polar surfaces o... more ZnO thin films were grown by metal-organic chemical vapor deposition on Zn-and O-polar surfaces of ZnO substrate. The effect of Zn-and O-polar substrate on the surface morphology and opto-thermal proprieties has been studied. Hall-measurements were used to determine the carrier concentration of the deposited films. Photothermal deflection spectroscopy (PDS) was used to determine the optical absorption spectrum and the gap energy by comparing experimental amplitude of the photothermal signal to the corresponding theoretical one. Thermal conductivity and diffusivity were also deduced from the photothermal deflection measurements. The found values were very low due to the thermal resistivity of the layer-substrate interface.

In this work, β-SnS 2 thin films have been prepared on glass substrates by the spray pyrolysis te... more In this work, β-SnS 2 thin films have been prepared on glass substrates by the spray pyrolysis technique using an alcohol solution which contains tin chloride (SnCl 4 ) and thiourea (SC(NH 2 ) 2 ) as precursors. The structural study shows that β-SnS 2 thin film prepared using optimal experimental conditions: substrate temperature T s = 280 °C and the concentration ratio of sulfur and tin elements in the spray solution x = [S]/[Sn] = 2.5, crystallizes in the hexagonal phase with a strong (001) X-ray diffraction line. In the same way, microprobe analysis (EPMA) as well as X-ray photoelectron spectroscopy (XPS) show the presence of undiserable phase of SnO 2 . From the transmission and reflectance spectra, the band gap energy is 2.65 eV. On the other hand, the photothermal properties of such films have been studied. Indeed, the analysis of β-SnS 2 thin films via the photodeflection spectroscopy including the effect of the inhomogeneity at the surface (roughness) and in the bulk (air in...

Materials Science and Engineering: A, 2010

Mechanical property measurements, positron annihilation lifetime (PAL) measurements and metallogr... more Mechanical property measurements, positron annihilation lifetime (PAL) measurements and metallographic observations, have been performed to study the isochronal annealing of commercial pure Cu in the temperature range from 25 up to 850 • C. A positive correlation has been found between positron lifetime ( ) and both the tensile strain ( L/L 0 ) and Vicker's microhardness (H v ). This correlation shows the presence of three annealing stages in commercial pure Cu which are attributed to recovery, recrystallization, and grain growth. These different stages were studied by both pure tensile and combined torsion-tension deformation for samples pre-annealed at the different annealing stages. Plastic instability behavior is observed in the case of combined torsion-tension deformation. It is observed that the onset and disappearance of this instability depend on some parameters such as mode of deformation, applied axial tensile stress and pre-annealing temperature.

International Journal of Photoenergy, 2012

... View at Publisher · View at Google Scholar · View at Scopus; M. Ghrib, M. Gaidi, T. Ghrib, N.... more ... View at Publisher · View at Google Scholar · View at Scopus; M. Ghrib, M. Gaidi, T. Ghrib, N. Khedher, M. Ben Salam, and H. Ezzaouia, “Morphological and optical properties changes in nanocrystalline Si (nc-Si) deposited on porous aluminum nanostructures by plasma ...

Journal of Magnetism and Magnetic Materials, 2015

ABSTRACT NiMn2O4 ternary nickel manganese oxide thin films spinels have been grown on glass subst... more ABSTRACT NiMn2O4 ternary nickel manganese oxide thin films spinels have been grown on glass substrates at 350 °C through spray pyrolysis technique. X-ray diffraction and Raman spectroscopy analyses show that the synthesized film has mainly cubic spinel structure with a preferred orientation along (111) plane. Some optical constants such as the refractive index (n), extinction coefficient (k), Urbach energy (EU=342 eV) and optical energy band gap (Eg=1.07 eV) have been calculated from reflection-transmission spectra. The mirage effect technique has been used to estimate the thermal conductivity (Kc). Its value is Kc=25 W m−1 K−1. The real part of the ac the conductivity behaviour has been investigated in the frequency range 100 Hz to 1 MHz. It was found that the real conductivity follows a power law (Aωs). The dc conductivity has been studied in the temperature range from 250 °C to 375 °C and supports the variable range hopping model proposed by Mott. The activation energy value estimated from the relaxation frequency is Ea~0.32 eV. Moreover, the temperature dependency of the resistance indicates that conduction was well described by a variable range hopping model, in which electron transfer takes place between Mn3+ and Mn4+ ions.

Physics Procedia, 2009

ABSTRACT The aim of this work is to investigate the influence of Si-doping on the optical, therma... more ABSTRACT The aim of this work is to investigate the influence of Si-doping on the optical, thermal and electrical properties of GaSb epitaxial layers. Such an influence was quantified through photoluminescence (PL), mirage effect (photothermal spectroscopy) and Hall effect measurements. Several GaSb samples, grown by Molecular Beam Epitaxy (MBE) on (100)-oriented GaAs semiinsulating substrates, with different Si-doping levels ranging from up to were tested. As a comparison, the same measurements were also performed on a GaSb non intentionally doped layer. The Hall effect data shows a monotonic decrease in carrier mobility when the hole concentration increase.The effect of band-to-band, band-impurity transitions on the PL gap E0 and the influence of high impurity concentration on the PL and absorption spectra have been also studied. Finally, the optical absorption changes induced by Si-doping on GaSb samples were investigated by photothermal deflection. It was shown that this technique allows a very precise deduction of the real interband gap energy of a semiconductor material as GaSb.Thermal conductivities were also deduced from the photothermal deflection measurements. The found values are very low due to the thermal resistivity of the layer-substrate interface but also due to the lattice-mismatch between GaSb epilayers and the GaAs substrate. However, the contribution of the free carriers to the thermal conductivity, with a high p-doping level (), could be highlighted.