Browsing by Author "Keffous, A."

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Aluminium-induced crystallization of amorphous silicon films deposited by DC magnetron sputtering on glasses
(2011) Kezzoula, F.; Hammouda, A.; Kechouane, M.; Simon, p.; Abaidia, Seddik-El-Hak; Keffous, A.; Cherfi, R.; Menari, H.; Manseri, A.
Amorphous silicon (a-Si) and hydrogenated amorphous silicon (a-Si:H) films were deposited by DC magnetron sputtering technique with argon and hydrogen plasma mixture on Al deposited by thermal evaporation on glass substrates. The a-Si/Al and a-Si:H/Al thin films were annealed at different temperatures ranging from 250 to 550 °C during 4 h in vacuum-sealed bulb. The effects of annealing temperature on optical, structural and morphological properties of as-grown as well as the vacuum-annealed a-Si/Al and a-Si:H/Al thin films are presented in this contribution. The averaged transmittance of a-Si:H/Al film increases upon increasing the annealing temperature. XRD measurements clearly evidence that crystallization is initiated at 450 °C. The number and intensity of diffraction peaks appearing in the diffraction patterns are more important in a-Si:H/Al than that in a-Si/Al layers. Results show that a-Si:H films deposited on Al/glass crystallize above 450 °C and present better crystallization than the a-Si layers. The presence of hydrogen induces an improvement of structural properties of poly-Si prepared by aluminium-induced crystallization (AIC)
Development of an Antireflection Layer Using a LDS Based on β-SiC Nanoparticles
(Springer, 2020) Benfadel, K.; Kaci, S.; Hamidouche, F.; Keffous, A.; Benmounah, A.; Manseri, A.; Achacha, S.
The main objective of this work is to use β-SiC (also called 3C-SiC) silicon carbide nanoparticles to formulate composite layer for wavelength conversion. Silicon Carbide nanopowders (npβ-SiC) were successfully synthesized by sol-gel method and followed by carbothermal reduction. Composite thin layers based on np-β-SiC incorporated into polyvinyl alcohol, (PVA) as matrix, where prepared. We have investigated the composite layers deposited silicon solar cell as a luminescent down shifting layer (LDS) to convert UV wavelengths. The texturation of the substrates by making pyramids, pyramids with nanowires was investigated in order to decrease the surface reflectance of silicon surface. An improvement in the spectral response of the obtained solar cells was very remarkable. In order to confirm this property, electro-optical characterizations were carried out on the solar cell with the developed composite layer and also on that without β-SiC/PVA coating, as reference. The morphological quality of the used substrates was examined by SEM images. EQE measurements have shown a noticeable increase showing the ability to use the prepared composite layer as lightweight encapsulation material for photovoltaic devices
Electrical characterization of ethanol sensing device based on vanadium oxide/Porous Si/Si structure
(Elsevier, 2013) Chebout, K.; Iratni, A.; Bouremana, A.; Sam, S.; Keffous, A.; Gabouze, N.
Photochemical conversion of CO2 into methyl alcohol using SiC micropowder under UV light
(2017) Azzouz, F.; Kaci, S.; Bozetine, I.; Keffous, A.; Trari, M.; Belhousse, S.; Aissiou-Bouanik, S.
In our study, microparticles SiC powder was investigated as a catalyst for CO2 photoreduction into methanol under UV light. The photochemical conversion of methanol was studied as function of time of exposition, the concentration and the grain size of the catalyst. The selectivity of the used catalyst to promote methanol formation was noticed. It was noticed also that the grain size and concentration have a great impact on the photochemical conversion of CO2 to methanol. The best yield of methanol was achieved when a concentration of 0.75 M of SiC powder of 17 m grain size and an exposure time to UV light of 2 h where assured. Maximum molar concentration of methanol achieved was under UV irradiation of 365 nm. Therefore, the catalytic property of silicon carbide has proved its efficiency in the photochemical conversion of CO2 into alcohol thus far under UV light
Properties of SiC-Based Luminescent Composite Thin Film As Light-Harvesting Material
(Springer, 2020) Benfadel, K.; Kaci, S.; Talbi, L.; Keffous, A.; Benmounah, A.; Bozetine, I.; Boukezzata, A.; Rahmoune, R.; Ouadah, Y.; Guerbous, L.; Kermad, A.; Achacha, S.; Mahmoudi, B.; Cheraga, H.
In this study, we present the use of SiC/PVA composite thin films as downshifting layers (LDS) in order to improve the photoelectrical parameters of a Si-based solar cell. We showed that the adding of these layers increases the short circuit current density. This increase could surely lead to the improvement of the power conversion efficiency since the two parameters are relied. The J–V characterizations of the as made c-Si solar cell measured under white light showed an enhancement of the photocurrent after coating the c-Si solar cell with SiC-based LDSs. The same behavior was noticed upon exposure to UV light illumination which depended strongly on the elaboration conditions of the luminescent porous SiC particles. A decrease in total reflectance of the c-Si solar cell coated with SiC based LDS was also observed. Spectral Response measurements have shown significant enhancement where the solar cells have poor optical response.