Ameur Zegadi - Academia.edu (original) (raw)

Papers by Ameur Zegadi

Recent developments in solar energy research have led to new technologies in solar cells. Materia... more Recent developments in solar energy research have led to new technologies in solar cells. Materials based on chalcopyrite ternary semiconductors have gained great interest because of their excellent optical properties. It has been shown that the compound’s defect structure affects strongly the optoelectronic properties of these alloys. In order to obtain more efficient devices these defects need to be detected and identified. The best way to characterize those novel materials is to use new techniques based on the exploitation of the photothermal effect. The main objective of this work is to study and implement an automated photothermal spectrometer. The first measurement technique that can be done with this apparatus is the photoacoustic spectroscopy. Wavelength scanning and data acquisition and logging are done automatically by a program written in LabVIEW. The second measurement technique is a transition from the former one. It is done by modifying only a few devices. Thus, one ca...

Journal of Electronic Materials, 2020

Near-stoichiometric CuInSe 2 thin films were synthesized by one-step electrodeposition on molybde... more Near-stoichiometric CuInSe 2 thin films were synthesized by one-step electrodeposition on molybdenum-coated glass substrates. Cyclic voltammetry measurements were firstly used to investigate the electrodeposition mechanisms. The electrochemical, structural, composition and nucleation properties of these films were investigated by cyclic voltammetry, scanning electron microscopy (SEM) and x-ray diffraction (XRD) using an energy dispersive xray spectrometer. Analysis of the nucleation mechanisms indicated that the electrodeposition of CuInSe 2 from a single bath solution involved an instantaneous 3-D nucleation. An appropriate deposition-imposed potential range of À700 to À400 mV/SCE was determined, although the reduction peak of indium occurred around À960 mV/SCE. The most suitable deposition potential for film preparation was determined to be À500 mV/SCE. The XRD results showed that the films exhibit a polycrystalline tetragonal CuInSe 2 phase with (112) orientation. The composition of the film deposited at À500 mV/SCE is very close to the stoichiometric ratio of 1:1:2 according to energy-dispersive xray spectroscopy measurements. We discuss the results obtained for the SEM and structural properties of the latter films, which were subjected to a postannealing process under vacuum at temperatures of 300, 400 and 500°C for 30 min.

Infrared Physics & Technology, 2020

This paper reports on a theoretical relation for the normalized photoacoustic amplitude signal fo... more This paper reports on a theoretical relation for the normalized photoacoustic amplitude signal for use in determining the optical absorption coefficient spectrum of any layer of multilayered semiconductors' samples. The derived relation is for use in gas-coupled photoacoustic cells. The model, unlike its predecessors so far reported in the literature that are usually for specific cases in dependence of the optical properties of the sample, takes into considerations the geometrical sample, the photoacoustic cell parameters, the thermal reflections as well as the light reflections at different interfaces. We present the results analysis on the effect of increasing the number of layers on the normalized photoacoustic response by considering particular applications in optoelectronic devices' configurations. A computer program has been developed to extract the absorption coefficient spectral distribution of any particular layer. Three specific experimental applications are provided in evaluating the performance of the present model. Unlike conventional spectroscopic techniques, the photoacoustic method is known for high detectability in the region of weak absorption. Hence, the applications we present here include the cases of a single transparent sample, a thin solid single crystal and embedded layer in a three-layered sample.

Arabian Journal for Science and Engineering, 2020

Solar cells based on Cu(In,Ga)Se 2 alloys as the absorber layer continue to attract attention in ... more Solar cells based on Cu(In,Ga)Se 2 alloys as the absorber layer continue to attract attention in research and industry. In order to reduce production costs, several deposition techniques have been employed, one of which is the electrochemical way. The paper reports on the synthesis in a single bath of low cost electrochemically thin films of the ternary semiconductor compound CuInSe 2 without the need to post-annealing treatments. We have studied the optimal parameters required for the electrodeposition of thin films on both molybdenum-coated glass (Mo) and silicon wafer substrates (Si). Metals salts of CuCl 2 , InCl 3 and SeCl 4 without added complexing agent were used to prepare close to stoichiometric composition of the chalcopyrite compound CuInSe 2. Thin films were electrodeposited at two imposed potentials − 0.4 and − 1 V/SCE. In addition to the electrochemical characterization methods, we have characterized our films using the X-ray diffraction technique (XRD), scanning electron microscope (SEM) and atomic force microscopy (AFM). The results indicate that the best films in terms of elemental composition, structure, crystallite size and morphology have been obtained with the imposed potential of − 1 V/SCE.

Emerging Materials Research, 2020

Emerging Materials Research Structural study and electrochemical deposition of a copper layer on ... more Emerging Materials Research Structural study and electrochemical deposition of a copper layer on n-silicon Khaniche, Zouaoui and Zegadi

Journal of Inorganic and Organometallic Polymers and Materials, 2020

In this work, we present a new method of synthesis of a polymer-MnO 2 composite. A film of poly [... more In this work, we present a new method of synthesis of a polymer-MnO 2 composite. A film of poly [4-(pyrrol-1-yl methyl) benzoic acid] denoted PPy-B is deposited on the surface of a vitreous carbon electrode by electrochemical oxidation of the corresponding monomer in acetonitrile solution. The carbon modified electrode was immersed in MnSO 4 aqueous solution to obtain the Mn 2+-polymer complex. The oxidation of the complex in Na 2 SO 4 aqueous solution leads to the formation of MnO 2 micro-particles within the polymer matrix. The effect of the pH, the concentration of MnSO 4 solution and the thickness of the polymer film on the amount of MnO 2 incorporated in the polymer film were studied. The presence of MnO 2 particles was confirmed by scanning electronic microscopy and energy dispersive X-ray spectroscopy. The electrical properties of the composite material were investigated by electrochemical impedance spectroscopy.

Infrared Physics & Technology, 2020

Abstract In this paper we describe a new photoacoustic cell design that allows simultaneous photo... more Abstract In this paper we describe a new photoacoustic cell design that allows simultaneous photoacoustic and photoconductive measurements of solid semiconductor samples. The two techniques are complementary. Photoacoustic spectroscopy is known for being a direct monitor of nonradiative de-excitation processes, while photoconductivity spectroscopy is a direct monitor on the photocurrent generated following the absorption of the radiation source. If used simultaneously, they should unveil valuable information on the properties of materials. As an application to the refined spectrometer we present a comparative study on the optical absorption properties of CuInSe2 single. The measurements were performed at room temperature close to the absorption edge. Appropriate theoretical models have been used to evaluate the absorption coefficient spectral dependence from measured data. The combined techniques showed varying sensitivities in detecting defects levels in different regions of the absorption spectrum of the compound, and thus offering more information on the defects structure of semiconductors in a quicker way.

Silicon, 2019

In this effort, a two-dimensional photonic crystal ring resonator (2DPCRR) is simulated. This dev... more In this effort, a two-dimensional photonic crystal ring resonator (2DPCRR) is simulated. This device is developed for temperature detection in harsh environmental conditions for temperatures ranging from 0°C to 360°C with high sensitivity. The sensor based on 2DPCRR hexagonal array of silicon (Si) rods surrounded by air. The detection principle based on the variation of the refractive index of the Si due to a change in temperature which changes the position of the transmission peaks. A shift is created that will be used to calculate the sensitivity. The OptiFDTD algorithm was used to simulate the transmission of light for different temperatures. The photonic band gap (PBG) studied using the plane wave expansion method (PWE). The results are promising because the simulated sensor has a high sensitivity (92.3 pm/°C) compared to the literature for an ultra-compact size, weight and energy consumption which is suitable for nanotechnology.

Journal of Electronic Materials, 2019

In this paper, we report an electrochemical study using cyclic voltammetry and chronoamperometry ... more In this paper, we report an electrochemical study using cyclic voltammetry and chronoamperometry on the kinetic and nucleation mechanisms of electrodeposited copper on indium-doped tin oxide-coated glass substrates from sulfate solutions. The present investigation has been carried out in an acid solution at pH = 5. The Scharifker-Hills model was used to analyze current transients. At relatively low overpotentials, copper deposition is observed to follow a model that involves instantaneous nucleation and diffusion-controlled 3D growth. The diffusion coefficient for Cu 2+ for various applied potentials is determined. Atomic force microscopy (AFM) has been used to check the surface morphology of the electrodeposited thin films.

Plasmonics, 2019

This paper reports on the design of a multipurpose photonic device based on 2-D photonic crystals... more This paper reports on the design of a multipurpose photonic device based on 2-D photonic crystals which uses Y couplers in its structure that is very efficient when employed as a switch in optical communication systems and possesses a very high sensitivity not only if used as a biophotonic sensor to detect refractive index changes but also as a pressure sensor to sense pressure changes. The performance of the device is analyzed in terms of photonic bandgap structure, transmission power, electrical field distribution, resonance wavelength, and sensitivity by making use of the methods of the plane wave expansion (PWE) and the finitedifference time-domain (FDTD). The design is optimized to allow maximum power transmission so no constraints are imposed on the device detector and to achieve high sensitivity in biosensors' applications allowing, thus, not only sensing very low analyte concentrations but also nondestructively detecting and analyzing nanoparticles. We propose here a highly efficient switching/ coupling device suitable for current optical communication systems with a transmission power that could reach 98.16%. If the same platform is used as a biosensor, it has a refractive index sensitivity of 1055 nm/RIU, the highest value so far reported in the literature. If used as a pressure sensor, it has a sensitivity of 23.057 nm/GPa in the pressure range 0 to 1 GPa, which is second highest sensitivity so far reported.

Arabian Journal for Science and Engineering, 2019

Intermediate oxides are synthesized by heating fresh lead dioxide obtained from commercial positi... more Intermediate oxides are synthesized by heating fresh lead dioxide obtained from commercial positive plates of lead-acid batteries. These oxides are soaked in sulfuric acid with 1.28 s g under stirring for 1 h. The obtained powders are analyzed using X-ray diffraction and chemical analysis. The samples are discharged with a cathodic current of 1 mA in sulfuric acid with 1.28 s g, and the capacity is determined. It is found that lead dioxide obtained from PbO 1.55 is more active than the fresh sample. It shows an increase in capacity of 17%. This is due to the increase in the quantity of structural water as given by the chemical and thermal analyses.

Infrared Physics & Technology, 2019

We report on the near infrared optical absorption properties of CuInSe 2(1 ± x) single crystals i... more We report on the near infrared optical absorption properties of CuInSe 2(1 ± x) single crystals in which small deviations (x) are introduced into the valence stoichiometry prior to the crystal growth using three spectroscopic techniques: transmission, photoacoustic and transmission-photoacoustic. Monocrystalline samples were cut from ingots grown using the Bridgman technique with the compositions: CuInSe 2 , CuInSe 1.787 , CuInSe 2.084 and CuInSe 2.212. The phases and crystallographic structures were checked from their corresponding powders using Xray diffraction. The optical properties were measured in photon energy range 0.7 to 1.2 eV. A comparison between the extracted absorption spectral distributions from different measurement methods is presented. Resolved peaks at photon energies higher than the compound bandgap close to the conduction/valence bands due to inter-bands transitions are detected from photoacoustic measurements. Also discussed are the defect levels observed in the spectra tail following the alloy starting composition change. It is shown that the sensitivity of photoacoustic operational modes to detect changes due to modification in samples' composition is higher than the transmission technique. Differences in spectral behavior with particular attention being given to the detected defects from different measuring operational modes are discussed.

Infrared Physics & Technology, 2019

In this paper, we investigate the presence of deep defect levels in as-grown p-conducting CuInSe ... more In this paper, we investigate the presence of deep defect levels in as-grown p-conducting CuInSe 2 single crystals using deep level transient spectroscopy, minority carrier transient spectroscopy and photoacoustic spectroscopy. The samples were cut from the middle of ingots grown by employing a vertical displaced Bridgman furnace. This material is attracting increasing interest in solar cells fabrication as the absorber layer. Aluminum Schottky contacts were deposited on the as-grown and etched material in an evaporation system pumped down to less than 10 −6 mbar. Three majority carrier traps were observed using deep level transient spectroscopy, and one minority carrier trap was detected by minority carrier transient spectroscopy. The concentrations of the traps have been estimated. The results hence obtained are compared to deep defect levels observed in the measured spectral dependence of the samples prior to junction's fabrication by using the technique of photoacoustic spectroscopy in the photon energy range 0.6 to 1.3 eV. The study shows a good agreement between the results of DLTS/MCTS to those of photoacoustic and to published data.

Journal of Electronic Materials, 2019

The manner in which CuIn(Se,S) 2 thin films were synthesized using a onestep electrodeposition me... more The manner in which CuIn(Se,S) 2 thin films were synthesized using a onestep electrodeposition method from an electrolyte bath is described. These were deposited on fluorine-doped tin oxide-coated glass substrates. Cyclic voltammetry was used to assess the deposition process. The films were postannealed in a vacuum atmosphere at 300°C for 1 h. The characterization techniques used in this study were x-ray diffraction, x-ray fluorescence, scanning electron microscopy, atomic force microscopy and UV-visible absorption spectroscopy. The characterization results show that the films have a good morphology, good crystalline structure, a high absorption coefficient close to the band edge, and bandgap energy of 1.44 eV. These properties are suitable for quality solar cell applications.

Infrared Physics & Technology, 2018

In this paper, we analyze the optical absorption properties of CuInSe 2 single crystals in the ph... more In this paper, we analyze the optical absorption properties of CuInSe 2 single crystals in the photon energy range 0.8 to 1.1 eV from measurements carried out at ambient temperature using the photoacoustic spectroscopy technique following post-annealing processes at the temperature range 100 to 300°C for a period of time of 30 min in various environments (vacuum, air and neutral). These are usually the most used media for thermal treatment. As-prepared thin films semiconductor materials usually require post-annealing in order to improve their structure and morphology to enhance their electronic properties. Despite the low temperatures and short period of the process, post-annealing is shown that it has an important impact on the absorption spectral behaviour of the compound. The potential of photoacoustic depth profiling operational mode carried out at two modulating frequencies (112 and 185 Hz) has been used to check on the samples' homogeneity in respect to depth defect populations distributions. A shift by 65 meV in the upper limit of the absorption coefficient spectrum due to a higher inter-band transition has been observed following the processes of post-annealing in air and in vacuum, whereas the process when carried out in a neutral environment the samples keep their band edge as prior to the treatment.

Plasmonics, 2018

A highly sensitive pressure sensor operating over a wide pressure range based on two-dimensional ... more A highly sensitive pressure sensor operating over a wide pressure range based on two-dimensional photonic crystals having a Mach-Zehnder interferometer structure has been developed. The plane wave expansion method (PWE) is used to determine the device operating wavelength range. The finite difference time domain method (FDTD) is used to calculate the device characteristic parameters such as the resonant frequency, the power transmission, and the sensitivity. The present sensor has two wide frequency ranges, a high sensitivity to refractive index changes and the highest detectable sensitivity pressure so far reported in the literature, that is, 25.06 nm/GPa. The present device has high and constant transmission power all over the entire pressure range 0 to 10 GPa. This is of practical importance since the constraints imposed on the sensing system (the light source and the photodetector) are the same.

Arabian Journal for Science and Engineering, 2017

In this paper, we used the finite-difference time domain method to analyze the wavelength spectru... more In this paper, we used the finite-difference time domain method to analyze the wavelength spectrum as detected at the end of two-dimensional photonic crystal waveguide that contains circle-and ring-shaped silicon rods distributed in an air wafer. A shift of 0.0758 µm in the wavelength position of the upper band edge, corresponding to a sensitivity of 758 nm/RIU, was observed. A local defect has been introduced, which produces a very high shift in the cutoff wavelength corresponding to a higher sensitivity of 1490 nm/RIU.

Optical and Quantum Electronics, 2016

In this paper, we used the 'PWE band solver' of the software package OPTIFDTD to find the photoni... more In this paper, we used the 'PWE band solver' of the software package OPTIFDTD to find the photonic band gap of 2D annular photonic crystal biosensor. A Terahertz frequency range has been observed. The relationship between the band gap and the refractive index, which has been shown graphically, allows as to calculating the sensitivity which has been achieved 1.8774 (THz/RIU), and identifying any unknown biological analyte. Widening the widths of the ring holes of purposed structure, improve a higher sensitivity.

Applied spectroscopy, 2017

Due to its impressive optical properties, lithium niobate (LiNbO3) is considered to be one of the... more Due to its impressive optical properties, lithium niobate (LiNbO3) is considered to be one of the most important ferroelectric materials. Its uses in sensing platforms require functionalization at the surface to enable the capture and quantifying of molecules. The current paper aims to demonstrate the covalent bonding of aminosilane layers to the LiNbO3 surface. Fourier transform infrared (FT-IR) analysis reveals the presence of an NbO-Si bond observable as a shoulder at the same wavenumber (975 cm(-1)) on the surfaces of LiNBO3 as well as on those of Nb2O5, using 3-(aminopropyl)trimethoxysilane (APTMS) or 3-(aminopropyl)methyldimethoxysilane (APDMS) precursors. This covalent bonding is confirmed by the insolubility of the silane coating in dimethyl sulfoxide (DMSO). A kinetic study of the aminosilane layer growth obtained by quantitative FT-IR analysis is also carried out.

Surface Review and Letters, 2016

In this paper, we have electrodeposited copper on polypyrrole surface. Results show that at high ... more In this paper, we have electrodeposited copper on polypyrrole surface. Results show that at high applied cathodic potential ([Formula: see text][Formula: see text][Formula: see text]1.8[Formula: see text]V), copper electrodeposition occurs with difficulties. The amount of electrodeposited copper is low (1.32%) and it is limited by the low polypyrrole conductivity. At this potential, poor conductivity is caused by its insulating state. However, at an applied cathodic potential of [Formula: see text]1.2[Formula: see text]V, the polypyrrole exhibits a relatively high conductivity and copper particles are electrodeposited with large amounts (12.44%) on polypyrrole/silicon system. At high applied cathodic potential, the SEM images show clearly dispersed grains of copper, but polypyrrole surface is less occupied. At an applied cathodic potential of [Formula: see text]1.2[Formula: see text]V, the SEM image shows that polypyrrole surface is homogenously more occupied with copper. After copp...

Recent developments in solar energy research have led to new technologies in solar cells. Materia... more Recent developments in solar energy research have led to new technologies in solar cells. Materials based on chalcopyrite ternary semiconductors have gained great interest because of their excellent optical properties. It has been shown that the compound’s defect structure affects strongly the optoelectronic properties of these alloys. In order to obtain more efficient devices these defects need to be detected and identified. The best way to characterize those novel materials is to use new techniques based on the exploitation of the photothermal effect. The main objective of this work is to study and implement an automated photothermal spectrometer. The first measurement technique that can be done with this apparatus is the photoacoustic spectroscopy. Wavelength scanning and data acquisition and logging are done automatically by a program written in LabVIEW. The second measurement technique is a transition from the former one. It is done by modifying only a few devices. Thus, one ca...

Journal of Electronic Materials, 2020

Near-stoichiometric CuInSe 2 thin films were synthesized by one-step electrodeposition on molybde... more Near-stoichiometric CuInSe 2 thin films were synthesized by one-step electrodeposition on molybdenum-coated glass substrates. Cyclic voltammetry measurements were firstly used to investigate the electrodeposition mechanisms. The electrochemical, structural, composition and nucleation properties of these films were investigated by cyclic voltammetry, scanning electron microscopy (SEM) and x-ray diffraction (XRD) using an energy dispersive xray spectrometer. Analysis of the nucleation mechanisms indicated that the electrodeposition of CuInSe 2 from a single bath solution involved an instantaneous 3-D nucleation. An appropriate deposition-imposed potential range of À700 to À400 mV/SCE was determined, although the reduction peak of indium occurred around À960 mV/SCE. The most suitable deposition potential for film preparation was determined to be À500 mV/SCE. The XRD results showed that the films exhibit a polycrystalline tetragonal CuInSe 2 phase with (112) orientation. The composition of the film deposited at À500 mV/SCE is very close to the stoichiometric ratio of 1:1:2 according to energy-dispersive xray spectroscopy measurements. We discuss the results obtained for the SEM and structural properties of the latter films, which were subjected to a postannealing process under vacuum at temperatures of 300, 400 and 500°C for 30 min.

Infrared Physics & Technology, 2020

This paper reports on a theoretical relation for the normalized photoacoustic amplitude signal fo... more This paper reports on a theoretical relation for the normalized photoacoustic amplitude signal for use in determining the optical absorption coefficient spectrum of any layer of multilayered semiconductors' samples. The derived relation is for use in gas-coupled photoacoustic cells. The model, unlike its predecessors so far reported in the literature that are usually for specific cases in dependence of the optical properties of the sample, takes into considerations the geometrical sample, the photoacoustic cell parameters, the thermal reflections as well as the light reflections at different interfaces. We present the results analysis on the effect of increasing the number of layers on the normalized photoacoustic response by considering particular applications in optoelectronic devices' configurations. A computer program has been developed to extract the absorption coefficient spectral distribution of any particular layer. Three specific experimental applications are provided in evaluating the performance of the present model. Unlike conventional spectroscopic techniques, the photoacoustic method is known for high detectability in the region of weak absorption. Hence, the applications we present here include the cases of a single transparent sample, a thin solid single crystal and embedded layer in a three-layered sample.

Arabian Journal for Science and Engineering, 2020

Solar cells based on Cu(In,Ga)Se 2 alloys as the absorber layer continue to attract attention in ... more Solar cells based on Cu(In,Ga)Se 2 alloys as the absorber layer continue to attract attention in research and industry. In order to reduce production costs, several deposition techniques have been employed, one of which is the electrochemical way. The paper reports on the synthesis in a single bath of low cost electrochemically thin films of the ternary semiconductor compound CuInSe 2 without the need to post-annealing treatments. We have studied the optimal parameters required for the electrodeposition of thin films on both molybdenum-coated glass (Mo) and silicon wafer substrates (Si). Metals salts of CuCl 2 , InCl 3 and SeCl 4 without added complexing agent were used to prepare close to stoichiometric composition of the chalcopyrite compound CuInSe 2. Thin films were electrodeposited at two imposed potentials − 0.4 and − 1 V/SCE. In addition to the electrochemical characterization methods, we have characterized our films using the X-ray diffraction technique (XRD), scanning electron microscope (SEM) and atomic force microscopy (AFM). The results indicate that the best films in terms of elemental composition, structure, crystallite size and morphology have been obtained with the imposed potential of − 1 V/SCE.

Emerging Materials Research, 2020

Emerging Materials Research Structural study and electrochemical deposition of a copper layer on ... more Emerging Materials Research Structural study and electrochemical deposition of a copper layer on n-silicon Khaniche, Zouaoui and Zegadi

Journal of Inorganic and Organometallic Polymers and Materials, 2020

In this work, we present a new method of synthesis of a polymer-MnO 2 composite. A film of poly [... more In this work, we present a new method of synthesis of a polymer-MnO 2 composite. A film of poly [4-(pyrrol-1-yl methyl) benzoic acid] denoted PPy-B is deposited on the surface of a vitreous carbon electrode by electrochemical oxidation of the corresponding monomer in acetonitrile solution. The carbon modified electrode was immersed in MnSO 4 aqueous solution to obtain the Mn 2+-polymer complex. The oxidation of the complex in Na 2 SO 4 aqueous solution leads to the formation of MnO 2 micro-particles within the polymer matrix. The effect of the pH, the concentration of MnSO 4 solution and the thickness of the polymer film on the amount of MnO 2 incorporated in the polymer film were studied. The presence of MnO 2 particles was confirmed by scanning electronic microscopy and energy dispersive X-ray spectroscopy. The electrical properties of the composite material were investigated by electrochemical impedance spectroscopy.

Infrared Physics & Technology, 2020

Abstract In this paper we describe a new photoacoustic cell design that allows simultaneous photo... more Abstract In this paper we describe a new photoacoustic cell design that allows simultaneous photoacoustic and photoconductive measurements of solid semiconductor samples. The two techniques are complementary. Photoacoustic spectroscopy is known for being a direct monitor of nonradiative de-excitation processes, while photoconductivity spectroscopy is a direct monitor on the photocurrent generated following the absorption of the radiation source. If used simultaneously, they should unveil valuable information on the properties of materials. As an application to the refined spectrometer we present a comparative study on the optical absorption properties of CuInSe2 single. The measurements were performed at room temperature close to the absorption edge. Appropriate theoretical models have been used to evaluate the absorption coefficient spectral dependence from measured data. The combined techniques showed varying sensitivities in detecting defects levels in different regions of the absorption spectrum of the compound, and thus offering more information on the defects structure of semiconductors in a quicker way.

Silicon, 2019

In this effort, a two-dimensional photonic crystal ring resonator (2DPCRR) is simulated. This dev... more In this effort, a two-dimensional photonic crystal ring resonator (2DPCRR) is simulated. This device is developed for temperature detection in harsh environmental conditions for temperatures ranging from 0°C to 360°C with high sensitivity. The sensor based on 2DPCRR hexagonal array of silicon (Si) rods surrounded by air. The detection principle based on the variation of the refractive index of the Si due to a change in temperature which changes the position of the transmission peaks. A shift is created that will be used to calculate the sensitivity. The OptiFDTD algorithm was used to simulate the transmission of light for different temperatures. The photonic band gap (PBG) studied using the plane wave expansion method (PWE). The results are promising because the simulated sensor has a high sensitivity (92.3 pm/°C) compared to the literature for an ultra-compact size, weight and energy consumption which is suitable for nanotechnology.

Journal of Electronic Materials, 2019

In this paper, we report an electrochemical study using cyclic voltammetry and chronoamperometry ... more In this paper, we report an electrochemical study using cyclic voltammetry and chronoamperometry on the kinetic and nucleation mechanisms of electrodeposited copper on indium-doped tin oxide-coated glass substrates from sulfate solutions. The present investigation has been carried out in an acid solution at pH = 5. The Scharifker-Hills model was used to analyze current transients. At relatively low overpotentials, copper deposition is observed to follow a model that involves instantaneous nucleation and diffusion-controlled 3D growth. The diffusion coefficient for Cu 2+ for various applied potentials is determined. Atomic force microscopy (AFM) has been used to check the surface morphology of the electrodeposited thin films.

Plasmonics, 2019

This paper reports on the design of a multipurpose photonic device based on 2-D photonic crystals... more This paper reports on the design of a multipurpose photonic device based on 2-D photonic crystals which uses Y couplers in its structure that is very efficient when employed as a switch in optical communication systems and possesses a very high sensitivity not only if used as a biophotonic sensor to detect refractive index changes but also as a pressure sensor to sense pressure changes. The performance of the device is analyzed in terms of photonic bandgap structure, transmission power, electrical field distribution, resonance wavelength, and sensitivity by making use of the methods of the plane wave expansion (PWE) and the finitedifference time-domain (FDTD). The design is optimized to allow maximum power transmission so no constraints are imposed on the device detector and to achieve high sensitivity in biosensors' applications allowing, thus, not only sensing very low analyte concentrations but also nondestructively detecting and analyzing nanoparticles. We propose here a highly efficient switching/ coupling device suitable for current optical communication systems with a transmission power that could reach 98.16%. If the same platform is used as a biosensor, it has a refractive index sensitivity of 1055 nm/RIU, the highest value so far reported in the literature. If used as a pressure sensor, it has a sensitivity of 23.057 nm/GPa in the pressure range 0 to 1 GPa, which is second highest sensitivity so far reported.

Arabian Journal for Science and Engineering, 2019

Intermediate oxides are synthesized by heating fresh lead dioxide obtained from commercial positi... more Intermediate oxides are synthesized by heating fresh lead dioxide obtained from commercial positive plates of lead-acid batteries. These oxides are soaked in sulfuric acid with 1.28 s g under stirring for 1 h. The obtained powders are analyzed using X-ray diffraction and chemical analysis. The samples are discharged with a cathodic current of 1 mA in sulfuric acid with 1.28 s g, and the capacity is determined. It is found that lead dioxide obtained from PbO 1.55 is more active than the fresh sample. It shows an increase in capacity of 17%. This is due to the increase in the quantity of structural water as given by the chemical and thermal analyses.

Infrared Physics & Technology, 2019

We report on the near infrared optical absorption properties of CuInSe 2(1 ± x) single crystals i... more We report on the near infrared optical absorption properties of CuInSe 2(1 ± x) single crystals in which small deviations (x) are introduced into the valence stoichiometry prior to the crystal growth using three spectroscopic techniques: transmission, photoacoustic and transmission-photoacoustic. Monocrystalline samples were cut from ingots grown using the Bridgman technique with the compositions: CuInSe 2 , CuInSe 1.787 , CuInSe 2.084 and CuInSe 2.212. The phases and crystallographic structures were checked from their corresponding powders using Xray diffraction. The optical properties were measured in photon energy range 0.7 to 1.2 eV. A comparison between the extracted absorption spectral distributions from different measurement methods is presented. Resolved peaks at photon energies higher than the compound bandgap close to the conduction/valence bands due to inter-bands transitions are detected from photoacoustic measurements. Also discussed are the defect levels observed in the spectra tail following the alloy starting composition change. It is shown that the sensitivity of photoacoustic operational modes to detect changes due to modification in samples' composition is higher than the transmission technique. Differences in spectral behavior with particular attention being given to the detected defects from different measuring operational modes are discussed.

Infrared Physics & Technology, 2019

In this paper, we investigate the presence of deep defect levels in as-grown p-conducting CuInSe ... more In this paper, we investigate the presence of deep defect levels in as-grown p-conducting CuInSe 2 single crystals using deep level transient spectroscopy, minority carrier transient spectroscopy and photoacoustic spectroscopy. The samples were cut from the middle of ingots grown by employing a vertical displaced Bridgman furnace. This material is attracting increasing interest in solar cells fabrication as the absorber layer. Aluminum Schottky contacts were deposited on the as-grown and etched material in an evaporation system pumped down to less than 10 −6 mbar. Three majority carrier traps were observed using deep level transient spectroscopy, and one minority carrier trap was detected by minority carrier transient spectroscopy. The concentrations of the traps have been estimated. The results hence obtained are compared to deep defect levels observed in the measured spectral dependence of the samples prior to junction's fabrication by using the technique of photoacoustic spectroscopy in the photon energy range 0.6 to 1.3 eV. The study shows a good agreement between the results of DLTS/MCTS to those of photoacoustic and to published data.

Journal of Electronic Materials, 2019

The manner in which CuIn(Se,S) 2 thin films were synthesized using a onestep electrodeposition me... more The manner in which CuIn(Se,S) 2 thin films were synthesized using a onestep electrodeposition method from an electrolyte bath is described. These were deposited on fluorine-doped tin oxide-coated glass substrates. Cyclic voltammetry was used to assess the deposition process. The films were postannealed in a vacuum atmosphere at 300°C for 1 h. The characterization techniques used in this study were x-ray diffraction, x-ray fluorescence, scanning electron microscopy, atomic force microscopy and UV-visible absorption spectroscopy. The characterization results show that the films have a good morphology, good crystalline structure, a high absorption coefficient close to the band edge, and bandgap energy of 1.44 eV. These properties are suitable for quality solar cell applications.

Infrared Physics & Technology, 2018

In this paper, we analyze the optical absorption properties of CuInSe 2 single crystals in the ph... more In this paper, we analyze the optical absorption properties of CuInSe 2 single crystals in the photon energy range 0.8 to 1.1 eV from measurements carried out at ambient temperature using the photoacoustic spectroscopy technique following post-annealing processes at the temperature range 100 to 300°C for a period of time of 30 min in various environments (vacuum, air and neutral). These are usually the most used media for thermal treatment. As-prepared thin films semiconductor materials usually require post-annealing in order to improve their structure and morphology to enhance their electronic properties. Despite the low temperatures and short period of the process, post-annealing is shown that it has an important impact on the absorption spectral behaviour of the compound. The potential of photoacoustic depth profiling operational mode carried out at two modulating frequencies (112 and 185 Hz) has been used to check on the samples' homogeneity in respect to depth defect populations distributions. A shift by 65 meV in the upper limit of the absorption coefficient spectrum due to a higher inter-band transition has been observed following the processes of post-annealing in air and in vacuum, whereas the process when carried out in a neutral environment the samples keep their band edge as prior to the treatment.

Plasmonics, 2018

A highly sensitive pressure sensor operating over a wide pressure range based on two-dimensional ... more A highly sensitive pressure sensor operating over a wide pressure range based on two-dimensional photonic crystals having a Mach-Zehnder interferometer structure has been developed. The plane wave expansion method (PWE) is used to determine the device operating wavelength range. The finite difference time domain method (FDTD) is used to calculate the device characteristic parameters such as the resonant frequency, the power transmission, and the sensitivity. The present sensor has two wide frequency ranges, a high sensitivity to refractive index changes and the highest detectable sensitivity pressure so far reported in the literature, that is, 25.06 nm/GPa. The present device has high and constant transmission power all over the entire pressure range 0 to 10 GPa. This is of practical importance since the constraints imposed on the sensing system (the light source and the photodetector) are the same.

Arabian Journal for Science and Engineering, 2017

In this paper, we used the finite-difference time domain method to analyze the wavelength spectru... more In this paper, we used the finite-difference time domain method to analyze the wavelength spectrum as detected at the end of two-dimensional photonic crystal waveguide that contains circle-and ring-shaped silicon rods distributed in an air wafer. A shift of 0.0758 µm in the wavelength position of the upper band edge, corresponding to a sensitivity of 758 nm/RIU, was observed. A local defect has been introduced, which produces a very high shift in the cutoff wavelength corresponding to a higher sensitivity of 1490 nm/RIU.

Optical and Quantum Electronics, 2016

In this paper, we used the 'PWE band solver' of the software package OPTIFDTD to find the photoni... more In this paper, we used the 'PWE band solver' of the software package OPTIFDTD to find the photonic band gap of 2D annular photonic crystal biosensor. A Terahertz frequency range has been observed. The relationship between the band gap and the refractive index, which has been shown graphically, allows as to calculating the sensitivity which has been achieved 1.8774 (THz/RIU), and identifying any unknown biological analyte. Widening the widths of the ring holes of purposed structure, improve a higher sensitivity.

Applied spectroscopy, 2017

Due to its impressive optical properties, lithium niobate (LiNbO3) is considered to be one of the... more Due to its impressive optical properties, lithium niobate (LiNbO3) is considered to be one of the most important ferroelectric materials. Its uses in sensing platforms require functionalization at the surface to enable the capture and quantifying of molecules. The current paper aims to demonstrate the covalent bonding of aminosilane layers to the LiNbO3 surface. Fourier transform infrared (FT-IR) analysis reveals the presence of an NbO-Si bond observable as a shoulder at the same wavenumber (975 cm(-1)) on the surfaces of LiNBO3 as well as on those of Nb2O5, using 3-(aminopropyl)trimethoxysilane (APTMS) or 3-(aminopropyl)methyldimethoxysilane (APDMS) precursors. This covalent bonding is confirmed by the insolubility of the silane coating in dimethyl sulfoxide (DMSO). A kinetic study of the aminosilane layer growth obtained by quantitative FT-IR analysis is also carried out.

Surface Review and Letters, 2016

In this paper, we have electrodeposited copper on polypyrrole surface. Results show that at high ... more In this paper, we have electrodeposited copper on polypyrrole surface. Results show that at high applied cathodic potential ([Formula: see text][Formula: see text][Formula: see text]1.8[Formula: see text]V), copper electrodeposition occurs with difficulties. The amount of electrodeposited copper is low (1.32%) and it is limited by the low polypyrrole conductivity. At this potential, poor conductivity is caused by its insulating state. However, at an applied cathodic potential of [Formula: see text]1.2[Formula: see text]V, the polypyrrole exhibits a relatively high conductivity and copper particles are electrodeposited with large amounts (12.44%) on polypyrrole/silicon system. At high applied cathodic potential, the SEM images show clearly dispersed grains of copper, but polypyrrole surface is less occupied. At an applied cathodic potential of [Formula: see text]1.2[Formula: see text]V, the SEM image shows that polypyrrole surface is homogenously more occupied with copper. After copp...