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Boughalmi R.,Tunis el Manar University | Boukhachem A.,Tunis el Manar University | Gaied I.,Institute Preparatoire Aux Etudes Dingenieurs Of Nabeul | Boubaker K.,Tunis el Manar University | And 2 more authors.
Materials Science in Semiconductor Processing

Silver sulfide (Ag2S) thin films have been deposited on glass substrates by t spray pyrolysis using an aqueous solution which contains silver acetate and thiourea as precursors. The depositions were carried out at a substrate temperature of 250 C. Structural studies by means of X-ray diffraction show that all tin (Sn)-doped Ag2S thin films crystallized in a monoclinic space group with noticeable changes in the crystallites' orientation. The discussion of some structural calculated constants has been made with Sn doping in terms of microhardness measurements. Moreover, the optical analysis via the transmittance, reflectance as well as the photocurrent reveals that the direct band gap energy (Egd) decreases (Egd varies from 2.34 to 2.16 eV) and the indirect band gap energy (Egi) increases (Egi varies from 0.98 to 1.09 eV) slightly as a function of Sn content. Electrical study shows that Sn doping changes the electrical conductivity and proves the thermal activation of electrical conduction. © 2013 Elsevier Ltd. Source

Trabelsi M.,Institute Preparatoire Aux Etudes Dingenieurs Of Nabeul | Militaru L.,Lyon Institute of Nanotechnologies | Savio A.,Lyon Institute of Nanotechnologies | Monfray S.,STMicroelectronics | Souifi A.,Lyon Institute of Nanotechnologies
IEEE Transactions on Electron Devices

In this paper, we present measurements of the random telegraph signal (RTS) noise and the low-frequency (LF) noise in metal-oxide-semiconductor field-effect transistors (MOSFETs) integrated in silicon-on-nothing (SON) technology. This paper takes the identification of traps responsible for the drain-current fluctuations by RTS and LF techniques. We extracted the positions and the capture cross section and activation energies of oxide traps in the interfacial layer (SiO2), as well as in the high-k dielectric (HfO2). Furthermore, it has been convincingly shown that this discrete switching of the drain current between a high state and a low state is the basic feature responsible for the l/fγ flicker noise in SON MOSFETs. © 2011 IEEE. Source

Gherouel D.,Tunis el Manar University | Gaied I.,Institute Preparatoire Aux Etudes Dingenieurs Of Nabeul | Amlouk M.,Tunis el Manar University
Journal of Alloys and Compounds

This work presents additional physical results about the enhancement of the heat treatment on AgInS2 sprayed thin films and the beneficial effect of the annealing in various atmospheres as reported recently by the same authors in J. Allows comp. 545 (2012) 190-199 [1]. Herewith, these ternary thin films have been subjected to an annealing process under air during 1 h for different temperature lying in 400-500 C domains. The X-ray diffraction analysis shows indeed that AgInS2 thin film prepared crystallizes in the chalcopyrite phase with a strong (1 1 2) line with the presence of orthorhombic phase as well as the presence of undesirables binaries phases such as Ag 2S and In2S3. The heat treatment in air atmosphere using 400 C reduced the undesirable binaries phases as well as the disappearing of the orthorhombic phase. In the same line, an improvement of the cristallinity has been obtained (Crystalline size = 90 nm). Moreover, this heat treatment leads to band gap energy of the order of 1.65 eV and finally, the electrical conductivity and thermal conductivity have been achieved: 1.14 Ω-1 m-1 and 0.71 W m-1 K-1 for 400 C as annealing temperature. © 2013 Elsevier B.V. All rights reserved. Source

Hamdi M.,Institute Preparatoire Aux Etudes Dingenieurs Of Nabeul | Ghanmi S.,Institute Preparatoire Aux Etudes Dingenieurs Of Nabeul | Benjeddou A.,Institute Superieur Of Mecanique Of Paris | Nasri R.,National Engineering School of Tunis
Journal of Intelligent Material Systems and Structures

A robust electromechanical updating methodology for piezoelectric structures effective coupling prediction is first presented. It combines a finite element design experiment-based a priori sensitivity analysis, a response surface method-based meta-modelling and a genetic algorithm-based multi-objective optimization procedure. Then, this methodology is applied to cantilever aluminium thick plate and thin beam structures that are bonded, respectively, with two oppositely poled large and oppositely and same poled small piezoceramic patches on their upper and lower surfaces. In order to correlate corresponding first few effective modal electromechanical coupling coefficients, a mechanical updating is first considered; it consists of identifying the stiffness parameters of linear springs, modelling the clamp, so that relative deviations between the first few experimental and finite element short-circuit frequencies are minimized; then, an electric updating is considered; it consists of finding the patches' relative transverse blocked dielectric constants that minimize the first few experimental and finite element open-circuit frequencies relative deviations. Free vibrations are simulated using ANSYS®-coupled piezoelectric three-dimensional finite element. The obtained results have partially confirmed those from a former ad hoc updating method since the sensitivity analyses led to same stiffness parameters' irreducible number and only some effective modal electromechanical coupling coefficient test-model correlations were enhanced. © The Author(s) 2013. Source

Benjeddou A.,Institute Superieur Of Mecanique Of Paris | Hamdi M.,Institute Preparatoire Aux Etudes Dingenieurs Of Nabeul | Ghanmi S.,Institute Preparatoire Aux Etudes Dingenieurs Of Nabeul
Smart Structures and Systems

Piezoelectric and dielectric behaviors of a piezoceramic patch adhesively centered on a carbon composite plate are identified using a robust multi-objective optimization procedure. For this purpose, the patch piezoelectric stress coupling and blocked dielectric constants are automatically evaluated for a wide frequency range and for the different identifiable behaviors. Latters' symmetry conditions are coded in the design plans serving for response surface methodology-based sensitivity analysis and meta-modeling. The identified constants result from the measured and computed open-circuit frequencies deviations minimization by a genetic algorithm that uses meta-model estimated frequencies. Present investigations show that the bonded piezoceramic patch has effective three-dimensional (3D) orthotropic piezoelectric and dielectric behaviors. Besides, the sensitivity analysis indicates that four constants, from eight, dominate the 3D orthotropic behavior, and that the analyses can be reduced to the electromechanically coupled modes only; therefore, in this case, and if only the dominated parameters are optimized while the others keep their nominal values, the resulting piezoelectric and dielectric behaviors are found to be transverse-isotropic. These results can help designing piezoceramics smart composites for various applications like noise, vibration, shape, and health control. Copyright © 2013 Techno-Press, Ltd. Source

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