Publications Internationales
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Item Characterization of Thin Layer SnO 2 /Glass by Neutrons Reflectometry(Scientific.net, 2009) Khelladi, Mohamed Fadel; Izerrouken, M.; Kermadi, Salim; Tala-Ighil, RazikaThe 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 temperatureItem 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, RazikaIn 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.Item 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, RazikaPure 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.Item 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/SiItem Numerical Simulation of Silicon Based Solar Cells with a Degenerated SnO2:F Window Layer(Cambridge Core, 2007) Tala-Ighil, Razika; Boumaour, MessaoudThe 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.Item 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) Tala-Ighil, Razika; Boumaour, Messaoud; Maallemi, Abderrezak; Melhani, KheiraItem Photoluminescence and structure of ZnO films deposited on i substrates by chemical spray deposition(2009) Sali, S.; Tala-Ighil, Razika; Kermadi, Salim; Kechouane, M.; Boumaour, MessaoudItem Neutron characterization of thin layer SnO2/Glass by neutrons reflectometry(2009) Khelladi, M. F.; Izerrouken, M.; Kermadi, Salim; Tala-Ighil, Razika; Sali, S.; Boumaour, MessaoudItem Sol-Gel synthesis of SiO2-TiO2 film as antireflection coating on silicon for photovoltaic application(2009) Kermadi, Salim; Agoudjil, N.; Sali, S.; Tala-Ighil, Razika; Boumaour, MessaoudItem High temperature annealing of sprayed SnO2 : F layers in a silicon solar cell process with screen-printed contacts(2006) Tala-Ighil, Razika; Boumaour, M.; Belkaid, M.S.; Mallemi, A.; Melhani, K.; Iratni, A.In order to improve the solar cell conversion efficiency, a thin film of doped tin oxide (SnO2: F) has been deposited by the spray-pyrolysis technique on a monocrystalline diffused silicon wafer. Subsequently, the layer must undergo the firing step of screen-printed contacts with temperatures up to 830 °C. After annealing, one notices with the naked eye the appearance of speckles disturbing the uniformity of the as-deposited blue-coloured SnO2:F. Characterizations such as XPS, FTIR, RBS, XRD, SEM, Hall Effect, four point probe...etc, are all consistent to reveal a net increase of the SnO2:F layer resistivity which leads to efficiency degradation. Annealing the thin films under CO and 90% N2–10% H2 atmospheres was investigated to seek possibilities to preserve the expected improvements. Unlike forming gas, CO reducing ambient was found to be very effective for the high temperature contact firing with no thin film conductivity deterioration