Publications Scientifiques

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Start date: 2000End date: 2009Has files: No

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    Analog Fault Detection based on Statistical Analysis
    (Hal, 2000) Khouas, Abdelhakim; Derieux, Anne
    In analog circuits, process variations result in physical parameter variations. Simulated values must then be considered with there tolerance intervals. Consequently, contrarily to digital circuits where the outputs are either '0' or '1' such that we can decide without ambiguity whether a fault is detectable or not, for analog circuits the fault detectability is a vague problem as the fault can either be completely detectable, partially detectable or completely undetectable which makes it very diOEcult to take a decision. In order to solve this decision problem, we have introduced the probability to detect fault (PDF) function which allows to formalize the problem of analog fault detection under parameter variations
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    Optimized Statistical Analog Fault Simulation
    (2001) Khouas, Abdelhakim; Dessouky, Mohamed; Derieux, Anne
    A new statistical method for analog fault simulation is presented. The method takes into account process parameter variations and aims to reduce the number of the computational expensive Monte Carlo simulations often required during analog fault simulation. The technique is illustrated by means of a fifth-order low-pass switched-capacitor filter
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    The Effect of CO Reducing Atmosphere on the Structural and Optical properties of SnO2: F films Deposited on a Si( N+)/Si(P) solar cell
    (2006) Zair Tala-Ighil, Razika; Boumaour, Messaoud; Maallemi, Abderrezak; Melhani, kheira; Iratni, A.
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    Characterization of Thin Layer SnO 2 /Glass by Neutrons Reflectometry
    (Scientific.net, 2009) Khelladi, Mohamed Fadel; Izerrouken, M.; Kermadi, Salim; Tala-Ighil, Razika
    The thermal annealing behavior of the SnO2 thin films elaborated by sol-gel method has been studied by the neutrons reflectivity technique. From the fit of the experimental data using Parratt32 software program developed at HMI, Berlin, scattering length density, thickness and roughness are extracted. The obtained results show that the film thickness increases with the increasing annealing temperature, and the roughness is higher at 500 °C. Whereas, approximately, the same scattering length density is obtained after each annealing temperature
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    Contact Resistance Determination For Multi-crystalline Silicon Solar Cells By Using Transmission Line Method (TLM)
    (2008) Tala-Ighil, Razika; Sali, S.; Oussalah, Slimane; Boumaour, Messaoud
    he main objective in solar cells realization consists in increasing their performances. The mechanisms of this increase obey specific phenomena of physics. There is necessarily a contact resistance value behind each value of conversion efficiency. The question is how to quantify the contact resistance and what is its behaviour with different temperature profiles and consequently with the conversion efficiency. This work responds to all of these questions. We have taken square multicrystalline silicon wafers of 10 cm sides. These wafers have followed the traditional process steps i.e.: chemistry, diffusion, silicon nitride PECVD deposition and metallization of the front grid with TLM (Transmission Line Method) mask. The TLM measures are obtained using a test bench which includes a four-point prober and an analyzer. The contact resistance is deduced by the plot of the resistance versus the TLM line distance. It represents the R(D2), R(D3), R(D23), R(D4) and R(D34) where D2, D3, D23, D4 and D34 are the TLM distances. The TLM resistance is the half of the intersection of the slope R(D) with the y-axis. A profile of the evolution of the contact resistance versus the screen printing temperature annealing from 650°C to 800°C for the multi-crystalline silicon solar cells has been obtained.
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    Preparation and characteristic of low resistive zinc oxide thin films using chemical spray technique for solar cells application
    (2008) Sali, S.; Boumaour, Messaoud; Tala-Ighil, Razika
    In this paper, we present results concerning undoped and indium-doped zinc oxide (ZnO: In) thin films were grown on glass and Si substrates using the chemical spray technique. The effects of thickness (e), as well as the substrate temperature (Ts), were studied. It was revealed by X-Ray diffraction that the preferred orientation of polycrystals is along C-axis, with hexagonal wurtzite structure. Two important facts were calculated from RBS measurements: the dopant concentration throughout the film and the thickness of the films, it was found that the thickness increase with time of deposition. Under optimum deposition conditions a low resistivity and a high optical transmittance of the order of 2.8 × 10−4 Ω cm and 85 %, respectively, were obtained.
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    Effect of H2O Content on Structure and Optical Properties of TiO2 Thin Films Derived by Sol-Gel Dip-Coating Process at Low Temperature
    (2008) Kermadi, Salim; Agoudjil, N.; Sali, S.; Tala-Ighil, Razika
    Pure TiO2 thin films were prepared on the glass substrates by sol–gel dip coating technique with titanium (IV) isopropoxide including simultaneously acetylacetone and acetic acid as stabilizing reagents. The effect of the amount of water in the sol on structural and optical properties of TiO2 thin films was investigated. The structural and optical properties of post- sintered films for 1 hour at 500°C in air were investigated By X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis spectroscopy and ellipsometry. The results showed a simultaneous appearance of the rutile and the anatase phases with different rutile / anatase proportions for all samples. The increase of the water content leads to the decrease of rutile / anatase proportion. The crystalline size varies from 7.94 to 24.84 nm for the anatase phase and from 17.70 to 22.31 nm for the rutile phase. The optical measurements showed that the structure was strongly influenced by the water / alcoxides molar ratios. In comparison with the bulk material, the TiO2 thin films prepared by this way exhibit low refractive index in the range of 2.15 and high band gap energy narrowing from 3.88 to 3.95 eV for direct allowed transition and from 3.09 to 3.39 eV for indirect allowed transition according to the cristallinity degree and the rutile /anatase weight fraction.
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    Measurement of Square Resistance In Situ of SnO2: F Thin Film With Annealing at High Temperature Under Air
    (ICTP, 2008) Tahi, Hakim; Boumaour, Messaoud; Tala-Ighil, Razika; Belkaid, M. S.
    Thin films of fluorine doped tin oxide (SnO2: F), deposited by spray pyrolysis on silicon substrate, were characterized by the method of four points probe in situ during annealing at high temperature under air. The evolution of square resistance (in situ) with the annealing temperature was interpreted in terms of competition between electronic conduction and ionic conduction. A square resistance of 136�/□ is measured before annealing and after annealing at 900°C, the square resistance increases appreciably to reach 40k�/□. This increase is explained by the absorption of oxygen at the films surface and an increase in SiO2 thickness at interface SnO2/Si
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    Numerical Simulation of Silicon Based Solar Cells with a Degenerated SnO2:F Window Layer
    (Cambridge Core, 2007) Tala-Ighil, Razika; Boumaour, Messaoud
    The paper presents a numerical simulation of the behaviour of SnO{2}:F/Si(N+)/Si(P) solar cells. The simulation addresses in particular the question of the role of the window layer SnO{2}:F for the device performance. As beginning step, the transparent conductive oxide of SnO{2}:F must be modelled in order to introduce its parameters in simulation codes. Two approaches were employed: one empirical by collecting the experimental data of spray deposited SnO{2}:F while the second one is theoretical by using models of highly degenerate wide band gap semiconductors. The second step consists in injecting the deduced parameters of fluorine doped tin oxide in simulation codes. We use two well-known photovoltaic simulation codes as PC1D and SCAPS 2.5. A comparative study of the results of structures SnO{2}:F/Si(N+)/Si(P) and Si(N+)/Si(P) have been done with a confirmation in enhancing the conversion efficiency by SnO{2}:F window layer addition.
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    Optical properties of fluorine doped tin oxide annealed under air
    (2006) Tala-Ighil, Razika; Boumaour, Messaoud; Maallemi, A.; Melhani, K.
    Fluorine doped tin oxide thin film was deposited as window layer on diffused mono- crystalline silicon wafers (100) for photovoltaic purposes. At the time of screen printing metallization (1), thin films SnO2: F is confronted to an annealing under air for temperatures beyond 800°C. In order to study the optical properties of this transparent and conductive oxide TCO, thin film SnO2: F is deposited with spray pyrolysis technique on quartz blades to support the annealing of the screen printing metallization at high temperatures. Measured spectra of transmittance and reflectance are obtained by using the characterization by spectrophotometry from the Ultra-Violet to the Near-Infrared range wavelength. One can proceed to the optical parameters calculation by using the numerical and iterative Mueller method (2) to solve the non-linear equations