Fouaz Lekoui - Academia.edu (original) (raw)

Papers by Fouaz Lekoui

Revista Mexicana De Fisica, Aug 31, 2023

Pure ZnO, Ag doped ZnO and Ag-Fe co-doped ZnO were prepared using thermal evaporation. XRD analys... more Pure ZnO, Ag doped ZnO and Ag-Fe co-doped ZnO were prepared using thermal evaporation. XRD analysis confirms that all layers present a hexagonal wurtzite structure; however, there is a small shift in the peaks position due to the distortion of the film's lattice. Scanning Electron Microscopy (SEM) analysis reveals the morphological variation of the film's surfaces due to the doping. Pure ZnO and Ag:ZnO films have a nanostructured surface, however, Ag-Fe:ZnO films showed a smooth surface without any nanoparticles. Raman analysis showed the presence of A 1 (LO), E 2 (high) and local vibrational modes (LVMs) for all layers. Ultraviolet-visible spectroscopy (UV-VIS) analysis shows that the films have a good transparency and the bandgap decreases with ZnO doping from 3.80 eV to 3.78 eV and 3.70 eV, for pure ZnO, Ag:ZnO and Ag-Fe:ZnO films, respectively. The electrical properties confirm the semiconductor nature of ZnO films with a resistivity around 1.4 Ω.cm, and with Ag and Ag-Fe doping, the films behave like conductors with 1.4 × 10 −4 Ω.cm and 1.4 × 10 −3 Ω.cm, respectively. These results make the Ag:ZnO and Ag-Fe:ZnO thin films good materials for photovoltaic application.

Optical materials, Apr 1, 2024

Physica. B, Condensed matter, Apr 1, 2024

Materials Today Communications

Zeitschrift für Naturforschung A

In this work, we report an effective approach based on an artificial intelligence technique to in... more In this work, we report an effective approach based on an artificial intelligence technique to investigate the secondary ions mass spectroscopy (SIMS) profiles of boron, phosphorus and arsenic ions. Those dopant ions were implanted into n- and p-type (100) Silicon substrate using the ion implantation technique with energy of 100 and 180 keV. Annealing treatment was conducted at various temperatures ranging from 900 to 1030 °C for 30 min. The doping profile parameters such as the activation energy, diffusion coefficient, junction depth, implant dose, projected range and standard deviation were determined using particle swarm optimization (PSO) algorithm. The efficiency of this strategy was experimentally verified by the fitting between both real measured SIMS profile and predicted ones. In addition, a set of simulated doping profiles was generated for different annealing time to prove the ability of this approach to accurately estimate the above parameters even when changing the expe...

2023 International Conference on Advances in Electronics, Control and Communication Systems (ICAECCS), Mar 6, 2023

2022 2nd International Conference on Advanced Electrical Engineering (ICAEE)

Journal of Medical Engineering & Technology

Disposable face masks are among the personal protective equipment (PPE) that highly contribute to... more Disposable face masks are among the personal protective equipment (PPE) that highly contribute to protecting people in the context of the current COVID-19 pandemic. Health authorities recommend wearing a mask as a barrier measure to limit the spread of viral respiratory diseases. During the first waves of the pandemic, besides professional high-quality PPE, decontaminated disposable mask reuse and homemade cloth masks were allowed due to scarcities. This work introduces a simple method based on-time history of the differential pressure, and an easy to use the setup for the testing of different kinds of respiratory protective masks for the purposes of quality control and evaluation of air permeability performance. The standard mask testing method and the new proposed approach were then used to evaluate the effect of machine washing on the widely used type of disposable masks; namely the surgical (medical) face masks. The objective is to determine the number of acceptable washing cycles that this kind of mask can withstand before losing its performance in terms of breathability and airflow resistance. Other quality characteristics such as material (fibres) degradation and hydrophobicity are investigated. Degradation mechanisms due to washing cycles for the different mask constituent layers were studied by scanning electron microscopy (SEM) imaging. This work is an attempt to contribute to the determination of the reusability threshold of general-purpose disposable surgical type face masks thereby contributing to the reduction of environmental concerns. Results in terms of the studied above parameters suggest limiting the reuse of standard type surgical masks to only one machine washing cycle.

2022 19th International Multi-Conference on Systems, Signals & Devices (SSD), May 6, 2022

HAL (Le Centre pour la Communication Scientifique Directe), Oct 21, 2019

International audienc

Revista Mexicana de Física

Superhydrophobic surfaces are highly desired for several applications due to their exceptional pr... more Superhydrophobic surfaces are highly desired for several applications due to their exceptional properties such as self-cleaning, anti-icing, anti-friction and others. Such surfaces can be prepared via numerous methods including plasma technology [1-7]. Among plasma technology methods used to prepare these surfaces, the plasma enhanced chemical vapor deposition method, which provides the advantages of low cost, simple processing, and easy to form micro-nano structure. In this work, a treatment of surface paper for improving hydrophobicity using a PECVD technique was realized, paper substrates was treated by CH4 plasma , the substrates were held on a grounded substrate, with time variation of 5, 10, 15 and 20 min, while pressure and power have been kept constant at 8.10-2 and 100 W respectively. After deposition we proceeded to carry out structural and morphological characterization of the treated surfaces, by (SEM), AFM, FTIR and then through contact angle measurements. It is found t...

Bulletin of Materials Science

Brazilian Journal of Physics, 2022

Titanium aluminum nitride (TiAlN) thin films were deposited on glass and stainless steel substrat... more Titanium aluminum nitride (TiAlN) thin films were deposited on glass and stainless steel substrate using a reactive DC magnetron sputtering system, with a mixture of pure nitrogen and argon gases, for different deposition times of 3, 5, and
7 min. The structural properties like phase’s formation and transition, elemental composition, and vibration modes were investigated by X-ray diffraction, energy-dispersive X-ray analysis, and Raman spectroscopy. The morphological properties
were analyzed by scanning electron microscopy (SEM). The mechanical and tribological properties in terms of hardness and friction coefficient were determined using the nanoindentation technique and tribometer. It has been found that the films
without nitrogen content have a crystalline structure, while the TiAlN films obtained after 3 and 5 min of deposition time exhibit amorphous structures. Films deposited after 7 min of deposition time have TiAlN and oxide phases. The Raman
spectroscopy reveals the appearance of TO/LO and 2O modes for all layers and the acoustic modes of second order (2A) for only the TiAl films. SEM images show that the layer thicknesses do not change significantly; however, the film morphology
changes with deposition time and becomes denser. The composition of all layers shows an increase of N content and a decrease of Al content, which affect the film mechanical properties. Results from mechanical characterization confirm that
the hardness and Young modulus increase with increasing nitrogen content and decreasing Al content, while the friction coefficient significantly decreases.

Optical Materials, 2021

Abstract The control of the optical properties of ZnO nanostructured thin films by using differen... more Abstract The control of the optical properties of ZnO nanostructured thin films by using different dopant elements paves the way for the development of potential materials for photonic and optoelectronic applications. In this work manganese (Mn) doped ZnO thin films were fabricated by rapid thermal evaporation method on a glass substrate having the same Mn content level of ~10% and annealed at different temperatures. XRD analysis showed that the annealed layers have hexagonal wurtzite structure, however, the unannealed layers showed only Zn peaks without any preferential direction. The elemental analysis of the films has been investigated by XPS, which revealed the presence of Mn and oxygen atoms for all layers. In addition, it was observed by FIB-SEM that the morphology of thin films changed with the annealing temperature. For an anneal at 500 °C nanoneedles appeared. Raman spectroscopy showed E1 (TO) mode in the sample annealed at 500 °C which was attributed with the formation of nanoneedles structures. The optical transmission of the annealed films was in the range of 75–77% and the optical bandgap varied from 3.97 to 3.72 eV. These variations are related to the structural and morphological changes of the thin films with annealing temperature.

2014 North African Workshop on Dielectic Materials for Photovoltaic Systems (NAWDMPV), 2014

Zinc oxide (ZnO) is a well-known semiconductor material having very interesting physical properti... more Zinc oxide (ZnO) is a well-known semiconductor material having very interesting physical properties that place it among the most promising materials in different fields; such as optics, photovoltaics, electronics, and gas-detection. ZnO is a transparent conducting oxide that has a natural conductivity and a high transparency in the visible. In this work, we report the deposition ZnO-Ag thin films by thermal evaporation followed by heat treatment. A mixture of ZnO and pure (Ag) w as evaporated under vacuum on glass substrate. The deposited thin films were then annealed at 300 and 500 °C. Ag to increase the conductivity of maintaining the highest possible characterization of the deposited films was added in order ZnO films while transparency. The was carried out by XRD, SEM, Raman and spectrophotometry. The effect of Ag addition to ZnO on mechanical, optical and electrical properties of ZnO is discussed.