M. GUERMAT Noubeil

Due to their exceptional properties, zinc oxide (ZnO) thin films have demonstrated potential as transparent conducting oxides (TCOs), making them suitable for use in optoelectronics. To enhance the performance of this oxide, we have introduced tin (Sn) as a dopant in ZnO. We selected Sn for its conductivity and ability to easily replace zinc in the crystal lattice. In this work, pure and Sn-doped (0.5, 1, and 1.5 wt%) ZnO films deposited by spray pyrolysis were fully characterized. The effect of Sn doping on the structural, optical and electrical properties of ZnO has been investigated in order to improve the efficiency of solar cells. The X-ray diffraction analysis (XRD) determined that the thin films possess a polycrystalline structure, showing a preferential orientation along the (002) plane. Additionally, the Raman spectroscopy corroborated the presence of the wurtzite structure in all of the films. The increased Sn concentration improves the crystalline characteristics and increases crystallites size from 31.5 nm to 32.1 nm. The FESEM images reveal a granular composition of nanostructured spherical grains with increased density as a result of Sn doping. According to the AFM analysis, adding 1% Sn to ZnO led to a substantial decrease in roughness, going from 21.66 nm to 6.81 nm for pure ZnO films and 1% Sn-doped ZnO films, respectively. The optical analysis reveals that all thin films exhibit a high transparency, estimated at approximately 74%. Additionally, the direct optical gap of pure ZnO films increased from 3.25 to 3.29 eV with 1% Sn doping. The electrical properties of ZnO films are enhanced by the addition of Sn, achieving a low resistivity value of 3.18 × 10-2 Ω.cm and a high figure of merit (FOM) of 1.22 × 10-4 Ω-1 for the 1% Sn-ZnO thin film. These features make the 1% Sn-doped ZnO thin film a viable alternative for a transparent electrode in solar cells.

In this study, we investigate the influence of various solvents (distilled water, methanol, and ethanol) on the physical properties of Co3O4 thin films, elaborated via spray pyrolysis on glass substrates at 400°C with a deposition time of 10 min. Multiple characterization techniques were employed to analyze the film properties. XRD results revealed distinct structural differences among the films, showing that the film prepared with distilled water exhibited a polycrystalline structure with a preferred (311) orientation [1], whereas the films prepared with methanol and ethanol presented an amorphous structure. The film prepared with distilled water displayed a root-mean-square (RMS) roughness of 76.49 nm and a contact angle (CA) > 90°, indicating a hydrophobic nature, which is advantageous for absorber layers [1-2]. In contrast, the films prepared with methanol and ethanol demonstrated hydrophilic behavior, with CA < 90° and RMS values of 14.78 nm and 25.96 nm, respectively. UV-Visible spectroscopy analysis showed high transparency ( > 80%) for the methanol and ethanol-prepared films, while the film prepared with distilled water had low transparency at 3%, signifying high absorbance with an optical band gap of 1.31 eV. Electrical characterization revealed low resistivity for the distilled water-prepared film, measured at 7.916 × 10-1 Ω.cm. These findings suggest that distilled water is the most effective solvent for producing Co3O4 thin films with properties favorable for solar cell applications, particularly as an absorber layer.

Fingerprint recognition systems have shown some weaknesses related to security issues such as fake presentation attacks. Therefore, it is necessary to protect these systems against attacks by incorporating fingerprint liveness detection (FLD) algorithms that must be able to distinguish between live and fake fingerprints. In this work, we propose a deep learning framework for FLD. Specifically, deep neural networks based transfer learning is proposed to classify the fingerprint as live or fake fingerprint. The proposed method focuses on the important features of fingerprint, which allows enhancing the feature representation and suppresses the less relevant ones. We evaluated the proposed FLD on LivDet2023 database, and results, meticulously analyzed, unveil the superior performance of the proposed method. Notably, the proposed method with DensNet201 model attains an exceptional accuracy of 98.36% on the LivDet2023 dataset, surpassing other deep networks

In order to enhance the optoelectronic characteristics of zinc oxide (ZnO) thin films, we utilized the spray pyrolysis technique to prepare ZnO thin films with thicknesses varying from 350 nm to 914 nm with an increment in deposition time. Thin films were deposited on glass substrates at a temperature of 450◦C. Various characterization techniques have been employed to examine the structural, optical, and electrical properties of these films. The X-ray diffraction (XRD) analysis indicates the presence of the polycrystalline wurtzite phase of ZnO, with a preferential orientation along the c-axis. Additionally, it is noted that the strength of the (0 0 2) reflection increases until reaching an optimal thickness of 803 nm, indicating that this particular sample possesses the highest level of crystallinity. However, the intensity of the reflection diminishes as the film thickness continues to increase, reaching 914 nm. The UV–Vis spectroscopy measurements indicated that all samples exhibited excellent transparency in the visible spectrum, with a slight reduction observed as the film thickness increased. Additionally, the band gap exhibited a decrease from 3.27 to 3.24 eV. The Hall measurement results demonstrate that the electrical properties of the ZnO thin film are significantly influenced by its thickness, achieving a high conductivity value of 2.05 (Ω.cm)-1 for the ZnO thin film with a thickness of 803 nm makes it a potential candidate for applications in solar cell electrodes.

In this study, we elaborated and characterized thin films of undoped and magnesium-doped (1%, 2%, and 3%) cobalt oxide. These films were deposited on ordinary glass substrates at a temperature of 400 °C, with a deposition time of 5 min, using the spray pyrolysis technique. The main objective of this work was to investigate the influence of magnesium doping on the structural, optical, and electrical properties of Co3O4. X-ray diffraction (XRD) results showed that all films were polycrystalline with a cubic spinel structure [1-4], and there was a decrease in the crystallite size (D) with increasing doping. The optical transmission spectra of the Mg-doped Co3O4 film exhibited high transmittance in the 400 to 500 nm range. Specifically, the electrical resistivity showed a significant decrease, from 8.031 Ω.cm to 0.807 Ω.cm for undoped and 2% Mg-doped films, respectively. However, for Mg concentrations of 3%, the electrical resistivity increased to 0.8217 Ω.cm.

In this study, we conducted a thorough analysis of the impact of fluorine doping at concentrations of 2%, 4%, and 6% on the structural, optical, and electrical characteristics of undoped SnO2 films deposited using the spray pyrolysis technique. Various analytical methods were employed to assess these properties: X-ray diffraction (XRD) for structural examination, UV-visible spectrophotometry for optical evaluations, and the four-point probe method for electrical measurements. The XRD analysis revealed that the films deposited via spray pyrolysis exhibited a polycrystalline structure with a tetragonal rutile-type phase [1-4]. The pure SnO2 and SnO2:2%F films displayed a preferential orientation along the (110) plane, as indicated by the peak at 2θ = 26.84°. However, the films doped with 4%F and 6%F showed a change in orientation from (110) to (200). The addition of fluorine dopant resulted in increased transmittance, reaching a maximum of 83% for the SnO2:6%F film. Electrical analysis demonstrated that fluorine doping enhanced the electrical resistivity of the pure SnO2 film deposited via spray pyrolysis, achieving a low resistivity value of 7.11 × 10-2 Ω.cm. Based on these findings, it can be concluded that SnO2:6%F holds potential for use as a conductive transparent electrode in thin-film solar cells.

Nanocrystalline zinc oxide (ZnO) has garnered significant attention from researchers and industries due to its superior properties as an optoelectronic material, particularly in solar cells as a transparent electrode. Doping,
especially with tin (Sn) and co-doping with tin and cobalt (Co), can refine its optoelectronic properties. In this manuscript, we report on the optoelectronic properties of undoped ZnO thin films, as well as those doped with Sn
and/or Co, elaborated using a simple chemical pneumatic spray pyrolysis method on glass substrates. A 1 % Sn doping concentration was used, with Co doping concentrations of 0 %, 0.5 %, and 1 %. The effects of Sn and/or
Co doping concentration on the structure, morphology, optical, and electrical properties of nanocrystalline ZnO were studied using X-ray diffractometer (XRD), Raman spectroscopy, Field emission scanning electron micro
scopy (FESEM), UV–Vis–NIR spectroscopy and Hall effect measurements. All the films studied exhibit wurtzite ZnO structures with a predominant (002) orientation and no secondary phase, as confirmed by X-ray diffraction
(XRD) analysis. The Raman spectroscopy also reveals the presence of a wurtzite structure in all the films. The FESEM images reveal the kind and concentration of the dopants significantly influenced the surface morphology
of the films. The elemental analysis with energy dispersive X-ray analysis (EDS) analysis successfully detected the doping of Sn and Co. The analysis of UV–Vis spectroscopy provide that the optical band gap for the undoped ZnO film is 3.25 eV. This band gap increases upon doping and co-doping, reaching a peak value of 3.30 eV for the Sn:Co (1 %:0.5 %) co-doped ZnO film. The ZnO film shows an improvement in the electrical resistivity upon doping and co-doping with low resistivity value of 1.95 × 10− 2 Ω cm for the film (1%Sn, 0.5 % Co)–ZnO. The highest figure of merit (FOM) achieved is 1.41 × 10− 4 Ω− 1 for a ZnO thin film co-doped with (1 % Sn, 0.5 % Co). The existence of (1 % Sn, 0.5 % Co) film with improved optical gap, low electrical resistivity and high FOM supports its use in transparent conductive oxide applications.

This study aims to develop copper oxide (CuO) films on standard glass substrates using the spray pyrolysis technique and investigate the effect of different deposition times on their structural, morphological, wettability, optical, and electrical properties to enhance their optoelectronic characteristics. CuO thin films were fabricated at different deposition times (5 to 20 min) with a substrate temperature of 400 °C. X-ray diffraction (XRD) analysis confirmed the crystalline structure of all deposited CuO films, showing a monoclinic phase with preferential orientation along the (111) direction, indicating a well-ordered atomic arrangement. Atomic force microscopy (AFM) examination revealed the influence of deposition time on the surface morphology, with a low roughness value of 13.315 nm observed for the 10 min film compared to 19.432 nm for the 20 min film. Contact angle (CA) analysis showed a transition from hydrophilic to hydrophobic behavior as the deposition time increased, indicating significant changes in surface properties. This transition to a hydrophobic nature (CA = 105°) for the 20 min sample is important for protecting photovoltaic devices from humidity-related degradation, ensuring long-term reliable operation even in challenging conditions. The transmittance of the film in the visible region was low, indicating high absorbance of CuO. The optical gap decreased from 1.98 to 1.61 eV with increasing deposition time, making films suitable as absorber layers in solar cells. Electrical analysis showed improved conductivity with increasing deposition time, leading to a decrease in electrical resistivity (3.77 V.cm) and high charge density (1.269 x 1016 cm-3 ) for the 20 min film. Therefore, the 20 min deposition film with a hydrophobic character exhibited good p-type electrical semiconductor properties and efficient absorption of solar light, making it promising for thin film solar cell applications.

The manuscript details the application of spray pyrolysis for the deposition of an economically viable transparent conductive oxide film comprised of (Ni/Co) co-doped SnO2 on a glass substrate. The primary objective of this
research was to systematically examine the impact of Ni/Co co-doping on diverse properties of the SnO2 thin film. These properties encompassed the film’s structural composition, surface morphology, optical response, and
electrical behaviors. A comparison was made with pure SnO2 film, as well as SnO2 films doped with 3 %Ni and 1%Co. The results indicate that all the samples exhibited a tetragonal structureThe introduction of Co and Ni
atoms had no impact on the favored alignment of the (110) plane or the crystal structure of the SnO2 film. The crystallite size of the pure SnO2 film, as well as the (Co, Ni)-doped and (Ni/Co) co-doped SnO2 films, varied
within the range of 11 to 20 nm. Scanning electron microscopy (SEM) images were employed to assess how doping and co-doping influenced the surface characteristics of the films. The presence of pores and/or roughness
on the surface resulted in a hydrophilic character and a decrease in the contact angle for the doped films (Ni, Co). However, the co-doped film exhibited a hydrophobic characteristic due to the surface enhancement provided by SnO2:3 %Ni:1 %Co. The research also focused on the optical characteristics of the films, showing a positive impact with the proper incorporation of Ni and Co atoms into the SnO2 lattice. It was notably observed that the
addition of Ni and Co atoms improves the optical properties of the undoped transparent SnO2 film in the visible spectrum, with a high transmittance of 87 % achieved for the Ni-doped film. Furthermore, the hydrophobic
nature achieved by adding a concentration of 3 %Ni to the SnO2:1 %Co film enhances its optical transmission in the range of 300 nm to 750 nm. The SnO2 film shows an improvement in the electrical resistivity upon doping and co-doping with low resistivity value of 2.22 × 10− 2 Ω.cm for the film (3 %Ni/1 %Co)-SnO2. Drawing from these insightful results, the study proposes the potential utilization of (Ni/Co) co-doped SnO2 films as transparent electrodes in optoelectronic applications, especially in the manufacturing of thin film solar cells.

Our research is dedicated to synthesizing thin films of iron and bismuth oxide (BiFeO3) using spray pyrolysis, employing various solution flow rates. The precursor solution was prepared by dissolving bismuth nitrate and iron nitrate in distilled water, with concentrations fixed at 0.1 mol/l. The solution flow rate ranged from 300 to 500 μl/min. The composition and structure of the films were characterized using X-ray diffraction (XRD), while their optical properties were studied using UV-visible spectroscopy. The electrical conductivity, mobility, and carrier concentration of the films were assessed using Hall effect measurements. X-ray diffraction analyses indicate the formation of pure bismuth ferrite with a rhombohedral structure and no secondary phase. The crystallite size increases with increasing flow rates.The optical gap of the films varies in the range of 2.4–1.9 eV, which is suitable for solar cell fabrication. The films exhibit p-type conductivity, and their conductivity and free carrier concentration increase with the flow rates.

As part of this study, we elaborated and characterized samples of thin layers of cobalt oxide, doping them with diferent concentrations of nickel (2%, 4% and 6%). These flms were deposited on ordinary glass substrates at a temperature of 400 °C, with a deposition time of 5 min, using the spray pyrolysis technique. The main objective of this research was to explore the infuence of nickel doping on the physical properties of cobalt oxide. The
results obtained by Raman spectroscopy confrmed the presence of Co+2 cations located in tetrahedral sites and Co+3 in octahedral sites, thus validating the spinel-type cubic structure. Morphological analysis revealed that the incorporation of nickel into the Co3O4 thin flms, synthesized by spray pyrolysis, resulted in a signifcant transformation of the porous surface morphology. This transformation resulted in the transition from a porous structure to a dense and uniform confguration, characterized by nanofower grains. Analyzes by EDS spectrometry revealed peaks associated with the elements Co and O, thus confrming the composition of the flms. An improvement in the durability and overall performance of the solar device in humid environments by obtaining the hydrophobic character (CA=99°) for the Co3O4/6%Ni flm. The transmittance decreased with increased as a function of Ni concentration. Optical studies show direct band gaps Eg1 and Eg2 varying between 1.41 and 1.3 eV and between 2.09 and 1.99 eV respectively. Notably, the electrical resistivity experienced a signifcant decrease from 28.39 to 0.178 Ω.cm for the undoped and 2% Ni-doped flms, respectively. However, for Ni concentrations≥4%, the electrical resistivity increased from 3.47 to 10.2 Ω cm.

Spinel thin flms Co3O4 have been deposited at a temperature of approximately 400 °C using spray pyrolysis. The testimony process was carried out with diferent deposition times (4, 5, 6, and 8 min), indicating that the flms were grown for varying durations. The objective of varying deposition times of the thin flms of Co3O4 was to optimize the fabrication of a hetero-junction between Co3O4 and ZnO. XRD, SEM and Raman investigations showed that pure cubic Co3O4 with an irregular spindle shaped particles have been successfully obtained. The flms’ thickness increased under prolonged preparation times leading to a denser surface. The optical measurements revealed that the thin layer with a deposition time of 8 min atained a total absorbance of 98% in the apparent spectrum with a band gap of 1.27 eV. The I–V characteristics recorded of FTO/ZnO/Co3O4/Au cells
showed that all devices exhibiting a rectifying behavior with a perfect factor that varies between 3.87 and 1.64. Our results suggest that Co3O4 at 8 min with a carrier density of 2.414 × 1014 cm−3 and high absorbance is potentially a competitive hole transport material in spinel solar cells, and, the recorded characteristics of the photovoltaic phenomenon were noted a short circuit current of 1.302 mA, an open circuit voltage of 369 mV and a fll factor of 32%.

The impact of the molarity solution on this property of elaborated ZnO thin films coating on a metallic aluminum substrate are the aim of this present work. ZnO is the chosen material to be deposited in this work; it is one of the most used materials in the development of hydrophobic surfaces due to its interesting physical and structural properties. The samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (FEG-SEM) equipped with energy dispersive X-ray analysis (EDX) and a profilometer. The wettability properties of the synthesized films were analyzed by measuring the contact angle between the surface of studied films and a deposited water drop (WCA). XRD analysis and Raman spectroscopy show that ZnO is well synthesized by thermal oxidation in this present work, where the crystallization of the deposited layer increases with increasing solution molarity. The calculated crystallite sizes are in the nanometric scale and reach their maximum value for the prepared solution of 0.3 M with an average crystallites size of 32 nm. The obtained results show that the surface morphology strongly depends on solution molarity and has an effect on the hydrophobic properties of the elaborated ZnO thin films. The elaborated sample with solution of 0.2 M shows compact granular attached to each other with an average size of 200 nm. Measured surface roughness ranges from 7.653 mm to 0.526 mm. The shape and surface roughness of the prepared thin layers had an effect on the surface hydrophobicity. The largest measured contact angle of 135.72 °, was achieved with a solution molarity of 0.2 M with the greatest roughness indicate the best hydrophobicity of this sample.

In this study, we used thermal evaporation to deposit thin films of zinc oxide (ZnO). The films were then subjected to annealing at various temperatures ranging from 350 °C to 500 °C, with a fixed annealing time of 2.5 hours. The film thickness was kept constant at 300 nm. The morphological, optical properties and structural changes of the ZnO films were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and visible-ultraviolet spectroscopy (VIS-UV) techniques. The XRD pattern also confirmed that the ZnO films exhibited a hexagonal wurtzite crystal structure. The full width at half maximum (FWHM) values of the diffraction peaks decreased as the annealing temperature increased, indicating better crystallinity of the thin films at higher temperatures. SEM images show that the grain size of thin films tends to increase as the annealing temperature increases. The contact angles of the samples were significantly increased and the surface wettability of the layers changed from hydrophilic to hydrophobic after annealing temperature. The VIS-UV data showed that the ZnO films were transparent in the visible region. The optical transmittance slightly increased with increasing annealing temperature. The optical gap (Eg) of the films decreased as the annealing temperature increased. The calculated Urbach energy values indicated that the defects in the ZnO films decreased with annealing temperatures. Finally, the correlation between the structural, morphological, wettability and optical features of the samples was determined. The optical band gap was observed to correlate proportionally with crystallite size and inversely with Urbach energy as a function of annealing temperature

In the present work, we studied the effect of cobalt (Co) doping rate between 2 % and 6 % on the structural, optical and electrical properties of thin films from copper acetate (Cu(CH3COO)2·H2O) produced by spray pyrolysis. The results obtained during the various characterizations carried out (Raman, contact angle, UV-Visible and the Hall effect) show that our films have a monoclinic structure with the presence of a single CuO phase. The measured contact angles are less than 90° for the CuO undoped, CuO:2 %Co and CuO:4 % Co confirming the hydrophilic character of the films, as well as the 6 % doped film shows the hydrophobic character with a contact angle greater than 90° (θ = 97.41°). An improvement of the absorption by the reduction of the transmittance for the films doped with 2 % Co, 4 % Co and 6 % Co with a low value of the transmission obtained in this work for the CuO:6 % Co film equal to 7.34 %. A decrease in the values of the optical gap as a function of cobalt doping with a low value equal to 1.66 eV found for the thin layer of CuO:6 % Co. The electrical analysis shows that the conductivity increases with the addition of cobalt to the CuO with a high value for the film doped with 6 % (  7.246  10 – 1 (Ω.cm) – 1). So, CuO-doped 6% cobalt has good physical characteristics which allow it to be used as a layer absorbing solar radiation in thin-film solar cells.

The photovoltaic (PV) effect is used to directly convert solar energy into electricity, but the actual conversion of solar energy into Electricity depends entirely on the development of PV technologies. PV products in the market are dominated by silicon (Si) solar cells [1-2]. Thanks to technological advances, a record performance on solar energy conversion efficiency (PCE) of approximately 27% was achieved under solar illumination (AM 1.5G) in solar cells in monocrystalline Si [3]. The discovery of optoelectronic properties on inorganic transition metal oxide such as Co3O4 of the spinel type [4] and CuO has recently attracted great interest among scientists thanks to their fundamentally new methods for the direct conversion of solar radiation into electricity. In this work, the focus was on optimizing the structural, optical and electrical properties of CuO and Co3O4 thin films. The films were deposited on ordinary glass substrates using the spray pyrolysis technique, with a deposition time of 10 min. A comparative study was conducted to analyze the physical properties of the films. Structural analysis using X-ray diffraction revealed that both CuO and Co3O4 films exhibited a polycrystalline nature. CuO crystallized in a monoclinic structure belonging to the (C2/c) space group, while Co3O4 exhibited a spinel structure belonging to the (Fd3m) space group. No other phases were detected in the films. The UV-Vis characterization results indicated that both CuO and Co3O4 films exhibited low transmittance in the visible region (400 - 800 nm). CuO had a transmittance of 17%, while Co3O4 showed a significantly lower transmittance of 0.02%. Furthermore, the Co3O4 film had a low optical gap of 1.32 eV. In terms of electrical properties, the Co3O4 film demonstrated a low resistivity of 9.905 × 10-1 (Ω.cm), indicating good electrical conductivity. These results suggest that the Co3O4 layer may be considered as the best absorbing layer in thin film solar cells due to its favorable optical and electrical properties.

Converting solar energy into electricity is an attractive alternative to fossil fuels. Among the solar absorber and semiconductor materials used for the manufacture of photovoltaic cells we find : Si, CuInSe2 [1], CdTe [2] and GaAs [3]. However, certain specific elements oppose the development of these materials such as the indirect gap (for Si), the rarity and/or toxicity of the elements and the high cost price. The latest generation of photovoltaic systems made up of thin layers of semiconductor oxides based on transition metals which have strong potential to combat all the difficulties encountered in usual solar cells. A category of these oxides are: inorganic perovskites such as: Bismuth Ferrite (BiFeO3) [4] and Bismuth Manganite (BiMnO3) [5]. In this work, we optimized the structural, optical, morphological and electrical properties of thin layers of BiFeO3 and BiMnO3. All samples were deposited on ordinary glass substrates by the “spray pyrolysis” technique at deposition time equal to 10 min. To characterize these samples, we used several techniques, such as X-ray diffraction, UV-Visible spectroscopy, Raman and the Hall effect. Structural analysis by X-ray diffraction shows that BiFeO3 and BiMnO3 are polycrystalline with a crystallized nature in the following structures: rhombohedral and monoclinic which belongs to the space groups (R3c) and (C2) respectively. No other phases are detected for the BiFeO3 film demonstrating that the thin film is single phase while the BiMnO3 film shows evidence of Bi2O3 as a secondary phase, located at 2θ = 26.75°. The results obtained by the UV-Visible characterization of BiFeO3 and BiMnO3 show a low transmittance in the visible region and the optical gap were obtained in this work for the films of BiFeO3 (Eg = 2.02 eV) and BiMnO3 (Eg = 1.20 eV). Contact angle values chows a hydrophobic character (> 90°) for both films. The electrical study of the BiFeO3 and BiMnO3 thin films shows that the BiFeO3 film produced by spray pyrolysis is p-type, while the BiMnO3 film is n-type. A low resistivity was obtained for the BiMnO3 films of the order of 1.90 × 101 (Ω.cm).

Transition metal oxides (TMO) are interesting because of the electrical and magnetic properties they exhibit [1-4]. Depending on the electronic configuration of the metal ions and the structural geometries, the oxides can be insulators or semiconductors. Among the conductive metal oxides, there is cobalt oxide (Co3O4) which is one of the oxides of transition metals, p-type semiconductor [5]. It is stable at room temperature, crystallizes in the cubic spinel structure, with strong absorbance in the UV-VIS range, good electrical conductivity, high mechanical resistance and a direct band gap (1.5 to 2.6 eV) [5]. The present work, we studied the effect of solution flow rate on the structural, optical and electrical properties of thin films of Co3O4 deposited on glass substrates by the spray pyrolysis technique. We then carried out analyzes on the samples produced by different characterization techniques such as: X-ray diffraction, Raman spectrometry, UV-Visible spectroscopy and the Hall effect. Structural analysis by X-ray diffraction showed that the deposited layers have a cubic spinel-type structure with a preferred preferential orientation along the (311) plane when the flow rate increases. The Raman result confirms the presence of Co+2 cations located in tetrahedral sites and Co+3 in octahedral sites, which confirms the spinel-type cubic structure. Optical measurements showed that the deposited layer of Co3O4 for a flow rate of 500 μl/min has an absorbance of around 97% in the visible region with a band gap of 1.31 eV and a minimum resistivity measured is 7.916 × 10-1 (Ω.cm)-1.

Metal oxide nanocrystals such as ZnO, SnO2, CuO, TiO2, etc. have been widely studied for their potential applications in various energy and environmental sectors [1-3]. Among these, CuO is the most desirable and promising materials have higher optical absorption, relatively low raw material cost. The bandgap (Eg) ≈ 1.5 eV, which is very close to the ideal Eg of 1.4 eV for photovoltaic (PV) devices and considered a splendid absorber of sunlight. The introduction of impurities can effectively change the physical properties of the resulting thin films, researchers were encouraged to optimize the characteristics of CuO thin films using an appropriate dopant is also an effective strategy to improve the properties of PV devices. Uddin et al. [4] deposited thin films CuO/%Ni by spray pyrolysis method and modified the physical properties of the films. Gnanasekar et al. [5] used La to improve the photocurrent properties of CuO thin films deposited by spray pyrolysis for photosensor applications. Additionally, Baturay et al. [6] observed the effect of Co-doping on the electrical, optical and magnetic properties of CuO films. For the undoped thin films, the Eg = 1.43 eV; the bandgap increases to 1.44 eV in films prepared with 2.4 at% Co while Eg decreases to 1.42 eV with 6 at%Co. The conductivity type of CuO films changed from p-type to n-type for 3% Co doping. These various intriguing results sparked our interest in this particular CuO material. In this work, pure and Co-doped (2%, 4% and 6%) CuO films deposited by spray pyrolysis were fully characterized. The effect of Cobalt doping on the structural, optical and electrical properties of CuO in order to improve the efficiency of solar cells. Raman analysis confirmed that the deposited layers have a monoclinic structure. Analysis by the UV-Visible spectrophotometer shows a decrease in the transparency of the films produced with a low value of 7.34% for the CuO:6%Co film. The electrical characterization shows that cobalt doping improves the electrical conductivity by reducing the resistivity from 455.8 Ω.cm for the undoped film to 1.38 Ω.cm for the CuO:6%Co film.

In this study, we investigated the effect of the addition of dopants such as aluminum (2% Al) and molybdenum (2% Mo) on the structural, optical and electrical properties of ZnO films deposited by the spray pyrolysis. We used several characterization techniques to study our films, including X-ray diffraction (XRD) for structural analysis, a UV-visible spectrophotometer for optical properties, and the four-point method for electrical properties. The samples deposited showed that the films produced by the spray pyrolysis method were polycrystalline, with a hexagonal structure of the Wurtzite type. This was confirmed by the presence of an intensive peak corresponding to the orientation (002) located around the angle of 34.82° in the X-ray diffraction spectrum. No other phase was detected in the samples. The analysis carried out using the UV-visible spectrophotometer revealed that the doping with aluminum and molybdenum improves the transmittance of the ZnO film significantly with a large value obtained for the ZnO:2%Al film. Regarding the electrical properties, the electrical analysis showed that all the doped films exhibited an improvement in electrical conductivity compared to the pure ZnO film. The ZnO:2%Mo film in particular displayed a relatively low electrical resistivity, measured at 0.0313 Ω.cm. This study showed that the addition of dopants such as aluminum and molybdenum to ZnO films deposited by spray pyrolysis had a significant impact on their structural, optical and electrical properties. The doped films exhibited better transmittance, improved electrical conductivity, and could hold promise for applications such as thin-film solar cells.

We suggest a facial recognition-based encryption technique based on chaos theory products to increase the security and effectiveness of our encryption system. Key generation, face extraction, and encryption are the three processes in the procedure. Hashing is utilized to generate secret keys, and Histogram of Oriented Gradients (HOG) is employed to extract face data from the face image. The key stream created in the first step of the encryption process is applied, and the remaining keys are reduced using the semi-blocked product theory and XOR diffusion. In order to maintain algorithm security, the correlation of information across three channels is also taken into account. This technique is employed in a variety of settings, including some face-based access control systems and mobile phone facial recognition unlocking. According to the results, facial recognition-based image encryption is safe and simple to use.

In this work, we have developed thin layers: FTO, NiO and BiMnO3. We have characterized these layers using various techniques such as X-ray diffractometer, Raman spectrometry, contact angle measurements, UV-Visible spectrophotometer, and two-point probe measurements. Based on the results obtained from optoelectronic characterization and their interpretations, we have concluded that the films are suitable for use in fabricating the NiO/BiMnO3 junction. The I(V) analysis of the NiO/BiMnO3/FTO structure showed a rectifying behavior with an ideality factor equal to 1.75. The heat treatments (annealing at 250 and 300 °C for 1 hour) considerably improved the electrical properties of the structure by reducing the reverse current and the series resistance of the structure. These improvements are beneficial for achieving more efficient and reliable device operation.

In this work, Co3O4 thin films were fabricated using spray pyrolysis with different precursors: cobalt chloride hexahydrate (CoCl2•6H2O), cobalt nitrate hexahydrate (Co(NO3)2•6H2O), and cobalt acetate (Co(CH3COO)2•4H2O). The objective was to investigate the influence of these precursor solutions on the properties of the Co3O4 thin films. Other experimental parameters such as molarity (0.1M), substrate temperature (400 °C), and deposition time (10 min) were kept constant. Raman results show the fives Raman active modes Eg, 3F2g and A1g of Co3O4. This confirms the Co3O4 spinel-like cubic structure for all as-deposited films where Co+2 and Co+3 occupy the tetrahedral and octahedral sites of Co3O4, respectively. All the deposited films exhibit p-type conductivity with a relatively high conductivity. The film synthesized with cobalt nitrate precursor seemed to possess promising optical and electrical properties for potential use in thin-film solar cell applications.

Fingerprint is a crucial biometric trait thanks straightforwardness to its unique characteristics, high reliability, and low cost. This has led to a widespread use in border control applications as well as personal identification systems. Meanwhile, fingerprint recognition systems have shown some vulnerabilities related to security issues such as spoof presentation attacks. In order to protect these systems, fingerprint liveness detection has been regarded as a primary countermeasure for protecting the fingerprint recognition systems from spoof presentation attacks. Towards this aim, in this paper we propose a machine learning method to distinguish live fingerprints. In this study, we use Convolutional Neural Networks (CNN) for fingerprint liveness detection. More specifically, the proposed method combines Mobilenet for features extraction and SVM for fingerprint images classification. Experimental results on a publicly available dataset (i.e., LivDet 2023 dataset) show that the proposed framework for fingerprint liveness detection purpose achieve promising results. Most importantly, our cross-sensor
evaluation depicts that MobileNet-SVM approach showed very promising generalization capabilities, where an ACER equals to 1.67% was obtained

In the present work, the fabrication of a hydrophobic surface was carried out by thermal oxidation of thin layers of Zn deposited by electrodeposition on an aluminum substrate under air atmosphere at different temperatures between 400 °C and 500 °C. Structural analysis by XRD and Raman spectroscopy shows that increasing the annealing temperature leads to the formation of a considerable amount of ZnO on the aluminum substrate. ZnO-bound XRD peaks appear and Zn- and Al-bound peaks decrease. For TS = 400 °C and 500 °C, the films treated at are polycrystalline with a hexagonal structure of the Wurtzite type due to the existence of the more intense peak relating to the orientation (100) located around the angle 31.75 °. EDX analysis gives the chemical composition of these films and confirms the presence of zinc and oxygen in an almost stoichiometric composition. The morphological study of thin layers treated at 500 °C shows the coexistence of nanostructures in the form of deformed flowers, which leads to their hydrophobicity. The contact angle values measured are > 90° for the films treated at 400 °C and 500 °C, which confirms the hydrophobic nature with a high value obtained equal to 135°.

Pure ZnO, Zn0.97Mg0.03O, Zn0.96Mg0.03Mn0.01O and Zn0.90Mg0.03Mn0.01F0.06O nanocrystalline thin films were successfully elaborated on glass substrates using spray pyrolysis method. Structural proprieties were mainly investigated by X-ray diffractometer (XRD), Scanning electron microscopy (SEM), UV–Visible spectrophotometry and Hall effect measurement technique. The XRD spectra revealed the preferred orientation of the prepared polycrystalline along (002) reflection and showed the hexagonal wurtzite structure. A decrease in the crystallinity of Zn0.90Mg0.03Mn0.01F0.06O sample has been observed from 17.206 to 13.489 nm due to the change in its ionic size. SEM images highlighted the homogeneity of the prepared samples surface and proved their nanostructure morphology. For the doped 3%Mg, 1%Mn and 6%F polycrystalline, the obtained transmission spectra were higher than that of pure ZnO and a shift towards the lower wavelengths with a band gap of 3.31 eV has been observed for Zn0.97Mg0.03O film. A low electrical resistivity of about 1.33 × 10− 3 Ω.cm was measured for Zn0.90Mg0.03Mn0.01F0.06O thin film. Also, its photoelectric performance was proven to be significantly higher than that of the previously reported ZnO doped and co-doped thin films, which makes it a remarkable candidate for several optoelectronic devices.

In this study, a comparison of different samples of Co3O4 doped with transition metals (3%Ni, 3%Cu and 3%Mg) in order to improve their physical properties. Our elaborated samples were analyzed by Raman spectroscopy, UV-Visible spectroscopy and four-point. The Raman results show the presence of Co⁺² cations localized in the tetrahedral sites and Co⁺³ in the octahedral sites, which confirms the cubic spinel-like structure for all the elaborated films. The optical measurements showed that the deposited layers of Co3O4 doped with Ni or Cu exhibit a strong absorbance of 95% to 100% in the visible region with optical gap equal to 1.34 eV. This allows the use of cobalt oxide with these dopants (Ni and Cu) as absorbent layer in solar cells. However, the Mg-doped film has a high transmission ~ 65% in the visible region with a low resistivity (ρ = 0.07 Ω.cm) compared to other elaborate films which allowed the use of Co3O4/3%Mg as conductive transparent electrode in solar cells.

In this work, we present a comparative study of the structural, optical and electric properties of transparent conductive films of ZnO, Zn0.97Ni0.03O, Zn0.97Co0.03O and Zn0.97Mo0.03O elaborated by the spray pyrolysis method for temperature = 400 °C. For this, several techniques were used for the characterization of our films: X-ray diffraction (XRD) for the structural study, UV-visible spectrophotometer for the optical properties and the four-point method for the electrical properties. The samples deposited show that all films are polycrystalline with a hexagonal structure of the Wurtzite type with preferential orientation (002). The addition of the Mo dopant decreases the transmittance on the other hand the others doping improve the transmittance of pure ZnO with a maximum value equal to 92.54% for Zn0.97Ni0.03O. The optical gap values are in the range of 3.25-3.28 eV. The electrical analysis shows that the doped films improve the electrical conductivity compared to pure ZnO, with a low resistivity value for the cobalt-doped film (ρ = 0.0298 (Ω.cm)).

In this work, we characterized and studied the influence of adding the concentration of dopants to Nickel (3%Ni) and Molybdenum (3%Mo) on the structural, optical and electrical properties of ZnO deposited by the chemical bath deposition method. For this, several techniques were used for the characterization of our films: X-ray diffraction (XRD) for the structural study, UV-visible spectrophotometer for the optical properties and the four-point method for the electrical properties. The deposited samples show that films produced by the chemical bath deposition method are polycrystalline with a hexagonal structure of the Wurtzite type due to the existence of the more intense peak relating to the orientation (002) located around the 34.97°, with no other phase is not detected. Analysis by the UVVisible spectrophotometer shows that the addition of 3% Ni improves the transmittance by a value of 87.66%. The electrical analysis shows that all the doped films improve the electrical conductivity of the 100% ZnO film with a high value for the ZnO: 3% Mo film equal to 1.042 (Ω.cm)-1 . According to this
work, ZnO:3%Ni and ZnO:3%Mo films can be used as conductive transparent electrode in thin film solar cells.

In this work, thin films of pure SnO2 and doped with Nickel, Zinc or Fluorine were deposited on ordinary glass substrates kept at 400 °C by the spray pyrolysis method. The effects of dopant on the structure, morphology, optical and electrical properties of films have been studied by a number of different techniques: X-ray diffraction (XRD), Contact angle, UV-Vis spectroscopy and four-probe. All the layers have a tetragonal structure of the rutile type due to the presence of an intense peak of orientation (110) located around the 26° angle for all the films produced. The contact angles measured using water droplets were less than 90° for all the films produced, which proves the hydrophilic nature of our films, while the film doped with fluorine had a low contact angle (37°). The optical analysis by means of the transmittance revealed that the films depend on the type of dopant with an average value equal to 82.5% and that the doping favors the reduction of the optical gap. Finally, the electrical analysis shows that the resistivity decreases with the doping compared to the pure SnO2 film with a minimum value for the fluorine doping (ρ = 2.245 10-4 Ω.cm).

–In this work, we studied the effect of adding Molybdenum (Mo) (0.25%, 0.5% and 0.75%) on the structural, optical and electrical properties of thin films based on Zinc Oxide (ZnO) deposited by the spray pyrolysis method for a temperature = 450°C. The results obtained during the various characterizations carried out (XRD, UV-Visible, and the four points) show that the undoped and Modoped ZnO films are polycrystalline with a hexagonal structure of the Wurtzite type with a preferential orientation (002). The transmittance decreases as a function of %Mo compared to undoped ZnO. The optical gap values are in the range of 3.17-3.25 eV with a large Eg value for the ZnO:0.25%Mo. The values of the refractive index and the porosity are strongly related to the optical gap. Electrical analysis shows Mo affects electrical properties of ZnO film and adding Molybdenum to ZnO with low
concentration (0.25%) improves electrical conductivity (σ = 1.176 (Ω.cm)-1).

In this work, we studied the influence of doping (1% Nickel and 3% Cobalt) and co-doping (3%Ni/2%Co and 3%Ni/3%Co) on the physicochemical properties of the layers. Thins based on Tin Oxide (SnO2) produced by the ultrasonic spray pyrolysis technique. For this, several techniques were used for the characterization of our films: X-ray diffraction (XRD) for the structural study, UV-visible spectrophotometer for optical properties and the four-point method for electrical properties. The samples deposited show that our films are of a cassiterite (tetragonal rutile) structure with a preferential orientation (110) [1-2]. The value of the average transmittance around 78.30% with a large value equal to 85.65% for the film doped at 3% Ni. The values of the optical gap are in the range of 3.827 - 3.886 eV. Electrical analysis shows that the addition of Co and Ni with SnO2 improves the electrical conductivity of our elaborate films.

Polycrystalline films of undoped and fluorine-doped SnO2 (FTO) are deposited on a glass substrate by spray pyrolysis at 400 °C. The effects of fluor concentration (8, 10 and 12 %) on the structural, morphological, optical and electrical properties of FTO films are studied. Our XRD results show that F-SnO2 still has the same rutile structure as undoped SnO2 with improved crystallization for doped films, with no other phase detected. The measured contact angles are  90° for undoped and 8 % F doped films, which confirms the hydrophilic character, while other doped (SnO2:10 % F and SnO2:12 % F) films show the hydrophobic character at contact angle values of  90° and the super-hydrophobic (CA = 140°) for SnO2:12 % F thin film. A higher transmittance value of 83 %, a wide band gap equal to 3.9 eV, and lower disorder (287.68 meV) are observed for the 12 % F doped SnO2 film. In addition, electrical resistivity (), carrier concentration (n) and Hall mobility () are determined from Hall effect measurements and it is found that all the elaborated thin films have n-type conductivity. The lowest resistivity of 2.245  10 – 4 Ωcm and the highest Hall mobility of 24.55 cm2V – 1s – 1 are obtained at an F concentration of 12 %. The results suggest that the FTO film at 12 %F can be used as a transparent conductive oxide of the front electrode for film solar cells

The aim of the present study was to deposited and characterized Zn-doped SnO2 thin films for different weight concentrations (wt.%) 0, 3, 5 and 7% produced by spray pyrolysis. The characterization by XRD showed that the layers are polycrystalline in nature, with tetragonal structure of rutile type due to the presence of intense peak of orientation (110) located around the angle 26° for all the films produced. The variations in FWHM and the crystallite size were very well correlated. The SEM micrograph shows a relatively dense and smooth surface exhibited by the 3 wt.% doped film. This result can be explained by considering the following reasons: the substitution of the Sn+4 cations for the Zn+2 cations facilitate, the crystallite size increase and the decrease in defects. The contact angles measured using water droplets were less than 90° for all the films produced, which proves the hydrophilic characteristic of the films, meanwhile the film doped with 3 wt.% Zn had a high contact angle (88.09°). This result suggests that a doping concentration equal to 3 wt.% Zn can be considered as a critical concentration in changing the surface morphology of the Zn-doped SnO2 films produced. The analysis by UV-visible spectrophotometer showed a transmittance varying between 76 to 87% depending on the doping. The 3 wt.% Zn-doped SnO2 film was found to have high transmittance (87%) and better optical property with minimum resistivity (ρ = 0.044 Ω cm) among the deposited films. This work demonstrated that the 3 wt.% Zn-doped SnO2 film improves the physical properties of the SnO2 film, allowing it to be integrated into the optoelectronic device.

This work reports on the development and characterization of Zinc Oxide (ZnO) layers deposited on glass substrates by spray pyrolysis method. The effect of 1%Mg-doping and 6%F/x%Mg co-doping (x=1, 2 and 3) on the structural, morphological, optical and electrical properties of the films obtained was studied. The structural characterization shows that all the deposited layers are polycrystalline with a hexagonal Wurtzite-type structure due to the existence of the more intense peak relative to the orientation (002) located around the angle 34.13 °, with no other phase is detected. The contact angles measured are more than 90° for pure, doped and 6%F/1%Mg co-doped films prepared confirmed the character hydrophobic and for the other co-doped (6%F:2%Mg and 6%F:3%Mg) films shows the hydrophilic character with values of the contact angle < 90°. An average transmittance was above 80% between 300 and 800 nm with a high transmittance value of 86.47% for the 6%F:1%Mg co-doping, which improves the properties. Co-doping with 1% Mg considerably improves the electrical conductivity (σ = 0.030 (Ω.cm)
-1 ). The results of our specifications suggest that the co-doped ZnO film (6% F, 1% Mg) can use as a buffer layer in solar cells.

This work the ZnO/8%F/1%Co/3%Mg thin film was deposited on ordinary glass substrates usingspray pyrolysis technique. The coated ZnO/8%F/1%Co/3%Mg films were annealed in air for 2hours at different temperatures of 400 °C, 450 °C, 500 °C and 550 °C. The films wereobtained at a concentration of solution is 0.1 mol/l. The objective of this study is to study theinfluence of annealing temperature (TA) on the the structural, optical and electrical properties of theZnO/8%F/1%Co/3%Mg thin films. The XRD analysis confirmed that the all films have a hexagonalWurtzite structure with a preferential orientation (100). The crystallite size varies between 12.857 nmto 20.516 nm for annealing temperatures varied between 400 °C to 550 °C, with a maximum value ismeasured of film annealed at 550 °C. The processed sample at different annealing temperatures showsan average transmittance of about 81% in the UV-Vis region. The optical gap varied from 3.28 eV to3.32 eV with annealing temperature. The maximum value of the electrical conductivity is 5.920(Ω.cm)-1 was obtained for the film annealed at 400 °C. The best estimated structural and opticalresults are achieved in annealed ZnO/8%F/1%Co/3%Mg film at 550 °C.

This work reports on the development and characterization of Zinc Oxide (ZnO) nanocrystalline thin films deposited on glass substrates by spray pyrolysis method. The effect of 1 % Mg-doping and 6 % F/x % Mg co-doping (x = 1, 2 and 3) on the structural, morphological, optical and electrical properties of the films obtained is studied. The structural characterization shows that all the deposited layers are polycrystalline with a hexagonal wurtzite-type structure due to the existence of a more intense peak relative to the (002) peak, located around an angle of 34.13° with no other phase detected. The measured contact angles are more than 90° for pure, doped and 6 % F/1 % Mg co-doped films prepared, which confirms the hydrophobic character, while other co-doped films (6 % F:2 % Mg and 6 % F:3 % Mg) show the hydrophilic character at values of the contact angle < 90°. A higher transmittance value of 86.47 %, a wide band gap of 3.53 eV and lower disorder (330.03 meV) are observed for the 6 % F:1 % Mg co-doped film. Co-doping with 1 % Mg considerably improves the electrical conductivity (σ = 0.030 (Ω.cm) – 1). The results suggest that the co-doped ZnO film (6 % F, 1 % Mg) can be used as a window film in thin film solar cells.

In this work, we have developed and characterized thin films of undoped and doped tin oxide (SnO2) with fluorine for different concentrations of 6%, 8%, 10% and 12% deposited by spray pyrolysis on glass substrates at a temperature of 400 °C, using Tin Chloride (SnCl2.2H2O) and Ammonium Fluoride (NH4F) solutions. The results of XRD characterization show that the layers are crystalline with a cubic structure due to the existence of the more intense peak relative to the orientation (111) located around the angle 31.69 ° for all deposited films [1]. Analysis by the UV-Visible spectrophotometer shows an increase of the transmittance (from 65% to 85%) and the optical gap (from 3.46 eV to 3.92 eV) [2] with a decrease of the refractive index (from 2.220 to 2.109) and the porosity (from 13.399% to 6.946%) as a function of F. For electrical characterization, the drack conductivity varied between 3.885 (Ω.cm)-1 and 79.103 (Ω.cm)-1 for Fluor doped films in the range 0% -12% [3]. Therefore, Fluorine is an important parameter used to improve the transmittance and conductivity of SnO2-based films produced by spray pyrolysis.

Due to the COVID-19 pandemic, automated contactless person identification based on the human hand has become very vital and an appealing biometric trait. Since, people are expected to cover their faces with masks, and advised avoiding touching surfaces. It is well-known that usually contact-based hand biometrics suffer from issues like deformation due to uneven distribution of pressure or improper placement on sensor, and hygienic concerns. Whereas, to mitigate such problems, contactless imaging is expected to collect the hand biometrics information without any deformation and leading to higher person recognition accuracy; besides maintaining hygienic and pandemic concerns. Towards this aim, in this paper, an effective multi-biometric scheme for person authentication based on contactless fingerprint and palmprint selfies has been proposed. In this study, for simplicity and efficiency, three local descriptors, i.e., local phase quantization (LPQ), local Ternary patterns (LTP), and binarized statistical image features (BSIF), have been employed to extract salient features from contactless fingerprint and palmprint selfies. The score level fusion based multi-biometric system developed in this work combines the matching scores using two different fusion techniques, i.e., transformation based-rules like triangular norms and classifier based-rules like SVM. Experimental results on two publicly available databases (i.e., PolyU contactless to contact-based fingerprint database and IIT-Delhi touchless palmprint dataset) show that the proposed contactless multi-biometric selfie system can easily outperform uni-biometrics.

In this work, the ZnO thin films were deposited on substrates heated in a temperature varied between 250 to 400℃ with a step of 50℃. The solution used for this deposition is composed of methanol and Zinc acetate. The XRD analysis confirmed that the deposited ZnO thin layers have a hexagonal wurtzite high quality with a preferential orientation (100) a-axis perpendicular to the substrate. The crystallite size is calculated using the Debye-Scherrer formula, the latter varies between 32-61 nm. Analysis by UV-Visible spectrophotometer is an important characteristic to assess the quality of the deposited layers. The prepared samples showed a high transmission which is higher than 82% in the UV-Vis region and also observed the presence of two phases leading to two different optical band gaps for substrate temperature at 250 and 300℃. The direct optical band gap energy calculated from the transmittance spectra was decreased with augmentation of substrate temperature. The minimum value of Urbach energy of ZnO thin film was achieved with 400℃. The measured contact angles are less than 90° for all the prepared samples confirming the hydrophilic character of all the films. The conductivity was ranged from 0.025 to 1.033 (Ωcm)-1 with increasing Ts.

This work deals with the preparation and characterization of pure and Nickel-doped porous Tin oxide (SnO2) thin films, using Spray pyrolysis technique for an eventual application in optoelectronics. The structural, morphological, optical, and electrical properties of these prepared samples were investigated using various techniques. X-ray diffraction analysis confirmed the tetragonal structure of pure SnO2 and Ni-doped films. The preferred orientation of the crystallites changed from (110) to (200) with the film doped at 15.3 at.% Ni, with crystallite size of about 10 and 18 nm for 15.3 at.% Ni-doped and 5.6 at.% Ni-doped SnO2, respectively. Scanning Electron Microscopy shows that the 15.3 at.% Ni-doped SnO2 film surface is relatively homogeneous, while the 5.6 at.% Ni-doped film is highly porous. The measured contact angles are less than 90° for all the prepared samples confirming the hydrophilic character of all the films. Transmittance as high as 85% in the visible region was observed for 5.6 at.% Ni-doped films, while lower transmittance is observed for 15.3 at.% Ni-doped films. A decrease of the optical band gap and the resistivity with increasing Ni dopant concentration were also observed.

The objective of this work is to develop Co3O4 films and to investigate the influence of different precursor concentration on the structural, morphological, optical and electrical properties of Co3O4 thin films, in order to improve the optoelectronic properties of these films. Finally, we have developed thin films of Co3O4 at different precursor concentrations (0.05 to 0.15 mol/l) under a substrate temperature set to 400°C and 4
minutes as deposition time. XRD analysis has shown that the deposited layers have a cubic spinel structure with a preferential orientation along the direction (311). The morphological studies have shown that the surface morphology of the films was almost homogeneous and dense. The presence of the peaks associated with the Co and O elements, which were present in the EDS analysis, confirmed the composition of the
films. The optical characterization of our film has shown a low transmittance (from 16 to 0.9%) in the visible region and the IR region varies between 40 to 2% over the range of precursor concentration varied between 0.05 and 0.125 mol/l and a high absorbance of the order of 100% for the film deposit of 0.15 mol/l. The obtained gap values are ranged from 1.44 to 1.52 eV and 2.05 to 2 eV for lower and higher energy regions in the range of precursor concentration 0.05–0.125 mol/l. The film prepared at 0.15 mol/l, had a good p-type electrical semiconductor and good absorbance of sunlight.

Biometrics is a scientific technology to recognize a person using their physical, behavior or chemical attributes. Biometrics is nowadays widely being used in several daily applications ranging from smart device user authentication to border crossing. A system that uses a single source of biometric information (e.g., single fingerprint) to recognize people is known as unimodal or unibiometrics system. Whereas, the system that consolidates data from multiple biometric sources of information (e.g., face and fingerprint) is called multimodal or multibiometrics system. Multibiometrics systems can alleviate the error rates and some inherent weaknesses of unibiometrics systems. Therefore, we present, in this study, a novel score level fusion-based scheme for multibiometric user recognition system. The proposed framework is hinged on Asymmetric Aggregation Operators (Asym-AOs). In particular, Asym-AOs are estimated via the generator functions of triangular norms (t-norms). The extensive set of experiments using seven publicly available benchmark databases, namely, National Institute of Standards and Technology (NIST)-Face, NIST-Multimodal, IIT Delhi Palmprint V1, IIT Delhi Ear, Hong Kong PolyU Contactless Hand Dorsal Images, Mobile Biometry (MOBIO) face, and Visible light mobile Ocular Biometric (VISOB) iPhone Day Light Ocular Mobile databases have been reported to show efficacy of the proposed scheme. The experimental results demonstrate that Asym-AOs based score fusion schemes not only are able to increase authentication rates compared to existing score level fusion methods (e.g., min, max, t-norms, symmetric-sum) but also is computationally fast.

Biometrics is now being principally employed in many daily applications ranging from the border crossing to mobile user authentication. In the high-security scenarios, biometrics require stringent accuracy and performance criteria. Towards this aim, multi-biometric systems that fuse the evidences from multiple sources of biometric have exhibited to diminish the error rates and alleviate inherent frailties of the individual biometric systems. In this article, a novel scheme for score-level fusion based on weighted quasi-arithmetic mean (WQAM) has been proposed. Specifically, WQAMs are estimated via different trigonometric functions. The proposed fusion scheme encompasses properties of both weighted mean and quasi-arithmetic mean. Moreover, it does not require any leaning process. Experimental results on three publicly available data sets (i.e. NISTBSSR1 Multimodal, NIST-BSSR1 Fingerprint and NIST-BSSR1 Face) for multi-modal, multi-unit and multi-algorithm systems show that presented WQAM fusion algorithm outperforms the previously proposed score fusion rules based on transformation
(e.g. t-norms), classification (e.g. support vector machines) and density estimation (e.g. likelihood ratio) methods.

In this context, we have deposited using spray prolysis technique on cleaned glass substrates a thin SnO2 layers using different deposition times from 3 min to 9 min and tin chloride
was used as starting solution with a molarity of 0.1 mol/l at temperature equal 350 °C. The main results of the deposition time effect on the structural and optical properties are:
Structural analysis of SnO2 film deposited at low deposition time revealed the presence of SnO phase. Moreover, increasing the deposition time, we noted the formation of the SnO2 orientation phase (111) with the absence of the SnO phase. The obtained films show good optical propertiest with an average transparency value greater than 60% in the visible region and the gap values varies between 3.98 to 3.5 eV.

SnO2-F thin films were prepared by spray pyrolysis technique at substrate temperature of 400 °C. A stannous chloride solution (SnCl2.2H2O) was used as precursor and ammonium fluoride (NH4F) as dopant with 8% [F]/[Sn] ratio. The effects of deposition times (5, 7, 9 and 11minutes) on the structural, optical, electrical and morphological properties of SnO2:8%F thin films were studied. X-ray diffraction (XRD) shows that the pure SnO2 and fluoride doped films are polycrystalline with a tetragonal crystalline structure. The films deposited showed 53-82% of transparency in the visible region depending on the time of deposition. The optical transmittance was 82% obtained from FTO glass subjected to a 5 minute deposited time at deposition temperature of 400 °C. In addition, Eg measured are varied between 3.83 to 3.53 eV for different deposition times. This diminution in values of optical gap is related to the carrier density reduction and/or crystallites size variation. The films deposited by FTO have the highest electrical resistivity for the spray technique which varies between 10-3 to 4 Ω / cm. The obtained results indicated that the structures, optical and electrical properties of the films were affected by the time deposition

In this research, SnO2 thin layers were developed by spray pyrolysis and tin chloride is used as a precursor with a morality of 0.1 mol/l. Results regarding the influence of the temperature changed from 250 to 400 °C on the properties of 100% SnO2 layers elaborated on glass substrates. The as deposited film exhibit a cubic structure with (002) preferential orientation and the crystallite size increased from 45 to 57 nm, according to substrate temperature. The results of the SEM have shown that the nanorods size is large when the substrate temperature is high. The obtained layers have good optical properties with a good transmittance in the visible range and the gap values vary between 3.59 and 3.83 eV; its indicating their photovoltaic applications.

In this work, we have elaborated and studied the optical, structural, morphological and electrical properties of the two oxides layers ZnO and SnO2 deposed by the spray pyrolysis technique prepared for a substrate temperature at 400 °C and a deposition time equal to 10 min with the concentration of 0.1 mol/l, in order to optimize the precursor which allows to have a high conductivity and high transmittance. The prepared thin films were characterized by UV-VIS Spectrophotometer, X-Ray Diffraction analysis (XRD) and electrical. The structural characterization of layer by analysis of the spectra of diffraction of the X-ray showed that the SnO2 film have cubic phase with preferential orientation (111) with a crystallite size equal to 57 nm. For the film of ZnO is polycrystalline in nature and the crystallite size at 12 nm. The UV-Visible spectrophotometer of these films confirms that it is possible to obtain good transparent films of SnO2 and ZnO with a transmittance of about 71% or 82% in the visible, respectively. The measurement of the electrical resistivity also showed that the resistivity value of the ZnO thin film improved by over that of the SnO2 film.

In this work, we studied the influence of doping (3% Cobalt and 1% Nickel) and doubly doping (2% Co / 3% Ni and 3% Co / 3% Ni) on the structural, optical and electrical properties of the Zinc oxide (ZnO) thin films deposited by spray pyrolysis technique prepared for a substrate temperature at 400 °C and a deposition time equal to 15 min with the concentration of 0.1 M, in order to optimize the optimal conditions which allows to obtained have a high conductivity and high transmittance. The results obtained during the different characterizations carried out (DRX, UV-Visible and the two points) show that our films are polycrystalline with a Wurtzite hexagonal structure with a preferential orientation (002). The average transmittance value around 85% with the presence of interference fringes in the visible range. The optical gap values are in the range of 3.26 - 3.28 eV. Electrical analysis shows that the conductivity increases with co-doping compared to pure ZnO film (0.29 (Ω.cm)-1 and 43.74 (Ω.cm)-1 of ZnO / 3% Ni / 2% Co and 67.16 (Ω.cm)-1 for ZnO / 3% Ni / 2% Co).

The drawbacks imposed by unimodal biometric systems can be mitigated using multiple biometric traits. In this study, a novel multimodal biometric system to authenticate users based on their major knuckle finger patterns using four fingers (i.e., little, ring, middle, and index) and iris is proposed. A local texture descriptor namely binarized statistical image features (BSIF) has been used to extract the features for each of the biometric traits considered in order to improve biometric-based personal verification. The comparison results on PolyU contactless hand dorsal images database and IIT Delhi-1 iris database indicate that the proposed multibiometric authentication with grouping function based score fusion outperforms the existing transformation-based fusion approaches in literature (e.g., t-norms, symmetric-sum), attaining a correct recognition rate of 95.54%.

We performed a comparative study of properties of the two oxides films ZnO and SnO2 deposed by the spray pyrolysis technique prepared at 400 °C of deposition temperature and a deposition time equal to 10 min with the concentration of 0.1 mol/l, in order to optimize the precursor which allows having a high conductivity and high transmittance. Several techniques were used for the structural, morphological, optical and electrical characterization of the films. The characterization XRD showed that the SnO2 film have cubic phase with preferential orientation (111) with a crystallite size equal to 57 nm. For the film of ZnO is polycrystalline in nature and the crystallite size at 12 nm. The transmittance is about 71% for the films deposited with SnO2 and around 81 % for films prepared ZnO these films confirms that it is possible to obtain good transparent ; the gap value obtained at 3.83 eV for SnO2 and 3.21 eV for ZnO. The refractive indexes were determined by ellipsometric measurements we have obtained values in the order of 2.304 and 2.146 for SnO2 and ZnO films respectively. The measurement of the electrical resistivity also showed that the resistivity value of the ZnO thin film improved by over that of the SnO2 film, is a remarkable result the use for photovoltaic applications.

This work aims at the elaboration and the characterization of thin films of tin oxide (SnO2) pure and doped with Nickel (2%, 4%, 6%, 8% and 10%) by the technique Spray pyrolysis, to study the influence of Ni on the properties of the films produced. The motivation for the use of this technique is its simplicity and the low cost. The results of the characterization obtained from XRD shows that the film produced from pure SnO2 shows a crystalline structure of the orthorhombic type by the presence of the following peaks the directions (110) and (200) are located in the angles 25.04 ° and 46.17 °, respectively. For the SnO2 film doped with 8% Ni we have a change of the tetragonal type structure according to the (110), (101), (200) and (211) planes. Raman vibrational characterization shows a Rutile phase for the Ni-doped films 4%, 6% and 10%. Analysis by the UV-Visible spectrophotometer shows an increase in the transmittance for the films as a function of doping with a high average value around 74% for the SnO2/10% Ni film. In addition, a growth in the optical gap and a decrease in Urbach's energy, the refractive index and the porosity with the increase in percentage of nickel doping in the film. The contact angle shows a hydrophilic character with values less than 90 ° for all the films produced. The electrical analysis shows a decrease in the conductivity and the concentration as a function of doping nickel.

One of the newest promising biometrics researched today is the vein
pattern recognition. However, little efforts have been invested in this direction.
In this paper, two frameworks focused on a palm and wrist vein-based
multimodal authentication system are proposed. For the first framework, wrist
and palm traits of the same hand are fused, whilst four biometric markers are
combined in the second framework using texture descriptors such as local
phase quantisation (LPQ), local binary patterns (LBPs), binarised statistical
image features (BSIF) and local ternary patterns (LTP). In addition, two
approaches of score level fusion are applied: 1) transformation-based using sum
rule, min-max rules and t-norms; 2) classifier-based via t-norms. The
experimental results on publicly available dataset show that the integration of
wrist and palm vein images from both left and right hand gives much improved
accuracy than the fusion of two traits of one hand. The recognition rate of the
proposed wrist-palm vein based multibiometric system is found to be 100%.