Papers by Author: F. Chaabouni

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Authors: F. Chaabouni, Luís Cadillon Costa, Mohamed Abaab, Jorge Monteiro
Abstract: ZnO is a wide band gap semi-conductor that has attracted tremendous interest for its potential applications in optoelectronic, solar cell, gas detection … In this work, aluminium doped zinc oxide (ZnO:Al) films were deposited by RF magnetron sputtering on glass substrates with different RF power densities of 1.2, 2.5, 3.7 and 4.9 W/cm2. We notice that the films grown at 1.2 W/cm2 were very thin and their physical properties were not precisely determined. The electrical properties of ZnO films were investigated using the impedance spectroscopy technique in the frequency range from 5 Hz to 13 MHz. The impedance data, represented by Nyquist diagrams showed that the resistivity of the films changed during the first three months after deposition. The deposited films show good optical transmittance (over 80 %) in the visible and near infrared spectra. The band gap is around 3 eV and decreases with the increasing of the RF power density (from 3.35 to 3.05 eV). The results of this study suggest that the variation of the RF power density used for deposition allow the control of the electrical and optical properties of the films
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Authors: Mabrouk Selmi, F. Chaabouni, I. Ben Mbarek, Mohamed Abaab, Bahri Rezig
Abstract: Titanium dioxide (TiO2) thin films were prepared by RF magnetron sputtering technique at an argon flow rate of 4.9 sccm and room temperature during 4 h. These films were deposited on pyrex substrates with an RF power of 300 W and annealed at different temperatures (500, 600, 700 and 800 °C). The optical and structural properties were studied by spectrophotometry and X ray Diffractometry respectively. The obtained results show an amorphous structure for the unheated TiO2 films and an apparition of an anatase phase after the annealing process. The transmittance is increased with an annealing of 500°C from 45 to 80 % in the visible and near-infrared regions. The direct band gap, refractive index, extinction coefficient and grain size were investigated. The reflection in the visible range for a silicon (Si(p)) substrate covered by TiO2 thin films is decreased to be about 20%. The results of this work suggest that the variation of the annealing temperature allow the control of the physical properties of TiO2 thin films as antireflective coating for silicon solar cells.
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Authors: Mabrouk Selmi, F. Chaabouni, Mohamed Abaab, Bahri Rezig
Abstract: RF magnetron sputtering is used to deposit Aluminum-doped zinc oxide (ZnO:Al) films on glass and p-Si substrates. This work is a study of ZnO:Al films grown at different RF powers for photovoltaic cells application, as antireflective (AR) coatings. At room temperature and argon gas pressure of 0.6 Pa, RF power was changed from 200 to 400 W. The structural, electrical and optical properties of ZnO:Al films were investigated. Under theses conditions, we have obtained c axis-oriented wurtzite structure ZnO thin films with high transmission (>85%) and low reflection in visible wavelength range and a band gap of 3.34 eV. The results of this study suggest that the variation of the RF power, used for growth, allows the control of the structural and optical properties of the films. ZnO:Al films can be used in optical applications as thin films antireflective coatings.
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Authors: F. Chaabouni, Luís Cadillon Costa, Mabrouk Selmi, Mohamed Abaab, Bahri Rezig
Abstract: TiO2 films were prepared using radio frequency (RF) magnetron sputtering and were deposited on glass and Si substrates. We varied deposition time at room temperature with RF density of 3.7 W/cm2 and argon flow rate of 4 sccm. The morphological, structural, optical and electrical properties were studied by Atomic Force Microscope (AFM), X ray Diffractometer (XRD) and UV-VIS-NIR spectrophotometer. The transmittance is maintained in the range of 70- 90% in the visible and near-infrared range, high refractive index of 2.4 and large direct band gap of about 3.5 eV are obtained. These films are annealed at 300°C during 2 hours. The annealing effect is investigated in this work. The results of this study suggest that the variation of the deposition time allow the control of the structural, optical and electrical properties of the films.
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