A5029036226- Organic Electronics and Photovoltaics
- Organic Light-Emitting Diodes Research
- Conducting polymers and applications
- Semiconductor Quantum Structures and Devices
- GaN-based semiconductor devices and materials
- Advanced Semiconductor Detectors and Materials
- Semiconductor materials and interfaces
- Luminescence and Fluorescent Materials
- Nanowire Synthesis and Applications
- Semiconductor materials and devices
- Silicon Nanostructures and Photoluminescence
- Photochemistry and Electron Transfer Studies
- Molecular Junctions and Nanostructures
- Organic and Molecular Conductors Research
- Metal and Thin Film Mechanics
- Quantum and electron transport phenomena
- Ga2O3 and related materials
- Nuclear Physics and Applications
- Acoustic Wave Resonator Technologies
- Radioactivity and Radon Measurements
- Perovskite Materials and Applications
- Spectroscopy and Laser Applications
- ZnO doping and properties
- Spectroscopy and Quantum Chemical Studies
- Advancements in Semiconductor Devices and Circuit Design
Tunis University
2014-2024
Tunis El Manar University
2014-2024
University of Monastir
1985-2012
Laboratoire de physique de la matière condensée
1993-1997
A pseudopotentiel formalism coupled with the virtual crystal approximation (VCA) is applied to study influence of composition on AxB1−xC ternary band gap in zinc blende phase. Our theoretical results show that gaps are affected by compositional disorder. We further predict bowing parameter II–VI, III–V and IV–IV alloys (i) has a close connection difference between lattice constants Δa; (ii) does not vary linearly electronegativities ΔXAB as case AIBIIC2VI chalcopyrite-structure (iii) scale...
The radioisotopic content of 17 samples natural and manufactured building materials collected in Tunisia have been analysed by using gamma spectrometry. From the measured ray spectra, activity concentrations are determined for (232)Th, (226)Ra, (235)U (40)K. total effective dose concentration index calculated applying criteria recommended European Union materials. results (232)Th (40)K found Tunisian indicate that radium thorium do not exceed 40 Bq kg(-1), but potassium varies between 50...
A set of measurements have been conducted in order to determine the annual effective dose resulting from ingestion natural radionuclides present eight different brands bottled water commercialised Tunisia. Using high-resolution gamma spectrometry technique, we noted presence following radionuclides: 214Bi, 226Ra, 228Ac, 212Pb, 235U and 40K. For all classes age, only radium concentration was found be significant calculation equivalent dose. Some studied samples exceeded reference level 0.1 mSv y−1
The role of intermolecular coupling and coherent electron-nuclear in the photophysics conjugated compound $\ensuremath{\alpha}$-quaterthiophene ($\ensuremath{\alpha}$-4T) has been investigated. For this purpose, we have measured photoluminescence (PL) spectra from $\ensuremath{\alpha}$-4T as a thin film (80 nm) single crystal. Singlet triplet excitons were brought into play using different excitation energies. By means Franck-Condon (FC) analysis, show that for film, PL is due to intrachain...
We present a theoretical study of band structure and optical gain spectra dilute-N InAsN/GaSb/InAsN the similar N-free InAs/GaSb/InAs laser structures, which have “W” alignment. Calculations are based on 10×10 k⋅p model incorporating valence, conduction, nitrogen-induced bands. The two diodes designed to operate at 3.3 μm room temperature. find that incorporation few percent nitrogen in active region improves performance, leads peak value approximately 1000 cm−1 for typical injection carrier...
Band-structure calculations are performed for cubic Al1−xGaxN using the empirical pseudopotential method. The band gaps at Γ, X and L points electron effective masses of Γ valleys calculated as a function gallium fraction x. It is found that there no significant change in these electronic parameters on taking into account alloy disorder. On basis model solid theory, we have discontinuities heterointerfaces between strained Al1 −xGaxN relaxed Al1−yGayN. latter extended to whole range...
Based on the empirical pseudopotential method within virtual crystal approximation combined with Harrison bond-orbital model, elastic and lattice vibration properties of GaN, ScN their hypothetical semiconducting alloys ScxGa1−xN in zinc-blende structure have been investigated. Quantities such as constants, bulk modulus, shear refractive index, dielectric constants optical phonon frequencies were calculated a function scandium molar fraction x. The agreement between present results known...
N , ′-Substituted quinacridones are a novel class of commercially available for organic electronics which reported here.
The electronic band-structure and optical gain properties of dilute-nitride InAsN/GaSb/InAsN type-II 'W' quantum wells based mid-infrared laser diodes on InAs substrate are numerically investigated with an accurate 10-bands kp model. designed to operate at 3.3 µm room temperature. dispersion relations, the threshold current density including computation non-radiative Auger recombination rate calculated. For typical injected carrier concentration 1.5 × 1018 cm−3 300 K, peak values order 1000...
Abstract Using the empirical pseudopotential approach, we have investigated electronic properties of GaN, ScN and their hypothetical alloys Sc x Ga 1− N in zinc‐blende structure. The band gaps at Γ‐, X‐ L‐points as well electron effective masses Γ X valleys were calculated a function scandium molar fraction . agreement between our results available experimental previously data is fair. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New dilute-nitride InAsN/GaSb laser diodes on an InAs substrate with a 'W' or 'M' design are theoretically investigated using ten-band k ⋅ p model including valence, conduction and nitrogen-induced bands. For these diodes, designed to operate at 3.3 µm room temperature, optical transition matrix elements for TE TM modes between the valence sub-bands sub-bands, modal gain total threshold current densities calculated. Under hypothesis of loss coefficient α = 50 cm−1, non-conventional...
Magnetoelectrical measurements were performed on a diode structure, based an anthracene-containing poly(arylene-ethynylylene)-alt-poly(arylene-vinylene) denoted AnE-PVstat, to clarify the role of recombination and dissociation electron-hole (e-h) pairs in magnetoconductance (MC). We report observed MC under weak magnetic field (<1 T) at room low temperatures. Positive is reaches up 2% 450 mT temperature. It found that with increase voltage, effect decreases. also difference between...
The correlation between the optical and morphological properties of an anthracene-containing poly(phenylene ethynylene)-alt-(phenylenevinylene) statistical copolymer (AnE-PVstat) in solution has been investigated. As a function temperature, molecular aggregation chloroform/chlorobenzene (CF:CB) was examined by means absorbance photoluminescence measurements. study evolution 0–0 to 0–1 (PL) ratio with temperature framework HJ-aggregate model unveiled presence both H- J-like behaviors at room...
We investigate the magnetic field effect on current of a diode based copolymer, poly{[4,4-bis(2-ethylhexyl)-cyclopenta-(2,1-b;3,4-b′)dithiophen]-2,6-diyl-alt-(2,1,3-benzo-thiadiazole)24,7-diyl} (PCPDTBT), which is intensively used in bulk heterojunction solar cells. Magnetoconductance measurements are carried out for applied voltages corresponding to trap-charge-limited regime. An effective mobility introduced take into account presence traps. The magnetoconductance positive and monotonic...
Pair-density-matrix theory has been adapted to the triplet-pair exciton annihilation under microwave excitation by including dimensionality of motion and applied fluorescence detected magnetic-resonance spectrum observed for a one-dimensional molecular crystal. This gives satisfactory fit effects on 1,4 dibromonaphtalene crystal leads determination singlet rate constant $\ensuremath{\lambda}$ triplet pair lifetime ${\ensuremath{\beta}}^{\ensuremath{-}1}$.
A theoretical approach, based on a pair-density matrix formalism, is developed for the study of dynamic triplet-pair annihilation in organic materials. Stochastic Liouville equation, taking into account effects static and magnetic fields, with superoperators representing coherent evolution, spin-independent rate, spin-dependent recombination, diffusion triplet exciton pairs, used. This approach applied to analyze fluorescence detected resonance (FDMR) spectra one-dimensional two-dimensional...