Said Dlimi - Academia.edu (original) (raw)

Papers by Said Dlimi

Research paper thumbnail of Analysis of thermoelectric effect of wet spun graphene fiber composites

International Journal of Low-Carbon Technologies

In this manuscript, we have theoretically reanalyzed data prepared and already published by Forou... more In this manuscript, we have theoretically reanalyzed data prepared and already published by Foroughi et al.[1]. These data concern the thermal energy dependence of the electrical conductivity of the samples: Graphene fiber, graphene/Poly(3,4-ethylenedioxythiophene)(graphene/PEDOT), graphene/ carbone nanotube(graphene/CNT) and graphene/carbone nonotube/Poly(3,4-ethylenedioxythiophene)(graphene/CNT/PEDOT) composite fibers. We investigate the behavior of the thermal conductivity for these four samples. These samples are considered as thermoelectric materials or green energy conversion materials using the Seebeck effect to transform heat into electrical energy and vice versa. In this context, the optimization of the ZT merit factor remains a challenge for the scientific community. The objective of this investigation is to evaluate and characterize the thermoelectric efficiency of the above-mentioned samples. We confront the experimental data with the existing theoretical models. The the...

Research paper thumbnail of Contribution of weak localization and electron-electron interaction, in corrective term “mT1/2” of the metallic conductivity in n-type SiAs

We present measurements of the electrical conductivity of barely metallic n-type SiAs that are dr... more We present measurements of the electrical conductivity of barely metallic n-type SiAs that are driven to the metal-insulator transition (MIT) by impurity concentration. The experiments were carried out at low temperature in the range (3.48 - 0.00044 K) and with impurity concentrations up to . On the metallic side of the MIT, the electrical conductivity is found to behave likedown to 0.44 mK. Physical explanation to the temperature dependence of the conductivity is given in metallic side of the MIT using a competition between two effects involved in the mechanisms of conduction, like electron-electron interaction effect, and weak localization effect.

Research paper thumbnail of Positive Magnetoresistance in Hydrogenated Amorphous Alloys Silicon Nickel a-Si1–yNiy:H at Very Low Temperature with Magnetic Field

We present results of an experimental study of magnetoresistance phenomenon in an amorphous silic... more We present results of an experimental study of magnetoresistance phenomenon in an amorphous silicon-nickel alloys a-Si1–yNiy:H (where y = 0.23) on the insulating side of the metal-insulator transition (MIT) in presence of magnetic field up to 4.5 T and at very low temperature. The electrical resistivity is found to follow the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T–1/2. This behaviour indicates the existence of the Coulomb gap (CG) near the Fermi level.

Research paper thumbnail of Negative Magnetoresistance Behaviour and Variable Range Hopping Conduction in Insulating NbSi Amorphous Alloys at Very Low Temperature with Magnetic Field

We present results of an experimental study of magnetoresistance (MR) in insulating NbSi amorphou... more We present results of an experimental study of magnetoresistance (MR) in insulating NbSi amorphous alloys sample showing Variable Range Hopping (VRH) conductivity. The MR is found to be negative in a wide range of low tem-perature (4.2- 20 K) and in the range of moderate magnetic fields (0- 4 T). We made tentative analysis using three theoretical models which are the model of quantum interference, the model of Zeeman effect and the model of localized magnetic moments

Research paper thumbnail of Analysis of the dielectric function of aluminum (Al) in bulk and nanometric states

Molecular Crystals and Liquid Crystals, 2020

We model the dielectric function of aluminum (Al). The modeling has been performed on Al in bulk ... more We model the dielectric function of aluminum (Al). The modeling has been performed on Al in bulk and nanometric states. First, we will model the experimental measurements of the dielectric constant as a function of the pulsation ω by appropriate mathematical functions in an explicit way. In the second part, we will highlight the contributions due to intraband and interband electronic transitions. In the last part, we model the dielectric constant of this metal in the nanometric state using several complex theoretical models such as the Drude Lorentz theory and the Drude two-point critical model. We shall comment on which model fits the experimental dielectric function best.

Research paper thumbnail of Modeling the Bulk and Nanometric Dielectric Functions of Au and Ag

Magnetic Skyrmions

In this work, we model the dielectric functions of gold (Au) and silver (Ag) which are typically ... more In this work, we model the dielectric functions of gold (Au) and silver (Ag) which are typically used in photonics and plasmonics. The modeling has been performed on Au and Ag in bulk and in nanometric states. The dielectric function is presented as a complex number with a real part and an imaginary part. First, we will model the experimental measurements of the dielectric constant as a function of the pulsation ω by appropriate mathematical functions in an explicit way. In the second part we will highlight the contributions to the dielectric constant value due to intraband and interband electronic transitions. In the last part of this work we model the dielectric constant of these metals in the nanometric state using several complex theoretical models such as the Drude Lorentz theory, the Drude two-point critical model, and the Drude three-point critical model. We shall comment on which model fits the experimental dielectric function best over a range of pulsation.

Research paper thumbnail of Efros–Shklovskii hopping in the electronic transport in 2D p-GaAs

Lithuanian Journal of Physics

We have investigated the resistivity of a 2D hole system in GaAs in the temperature range 200 mK ... more We have investigated the resistivity of a 2D hole system in GaAs in the temperature range 200 mK < T < 800 mK at zero magnetic field and low hole densities when the system is near the metal–insulator transition in the insulating side. We have found that the resistivity follows the Efros–Shklovskii variable range hopping (ES-VRH) law, this behaviour is consistent with the existence of a Coulomb gap. The resistivity scales with temperature and the prefactor has been found independent of temperature and density, thus confirming the dominance of hole–hole interaction.

Research paper thumbnail of Negative magnetoresistance behaviour and variable range hopping conduction in insulating NbSi amorphous alloys at very low temperature with magnetic field

Physical Chemistry of Interfaces and Nanomaterials XI, 2012

We present results of an experimental study of magnetoresistance (MR) in insulating NbSi amorphou... more We present results of an experimental study of magnetoresistance (MR) in insulating NbSi amorphous alloys sample showing Variable Range Hopping (VRH) conductivity. The MR is found to be negative in a wide range of low temperature (4.2-20 K) and in the range of moderate magnetic fields (0-4 T). We made tentative analysis using three theoretical models which are the model of quantum interference, the model of Zeeman effect and the model of localized magnetic moments

Research paper thumbnail of Variable range hopping conduction in insulating n-type InSb semiconductor

Physical Chemistry of Interfaces and Nanomaterials XI, 2012

Research paper thumbnail of Positive magnetoresistance in hydrogenated amorphous alloys silicon nickel a- Si1-yNiy:H at very low temperature with magnetic field

Physical Chemistry of Interfaces and Nanomaterials XI, 2012

We present results of an experimental study of magnetoresistance phenomenon in an amorphous silic... more We present results of an experimental study of magnetoresistance phenomenon in an amorphous silicon-nickel alloys a-Si 1-y Ni y :H (where y = 0.23) on the insulating side of the metal-insulator transition (MIT) in presence of magnetic field up to 4.5 T and at very low temperature. The electrical resistivity is found to follow the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T-1/2. This behaviour indicates the existence of the Coulomb gap (CG) near the Fermi level.

Research paper thumbnail of Study of electrical conductivity and scale theory in metallic n-type GeSb

Physical Chemistry of Interfaces and Nanomaterials XI, 2012

Research paper thumbnail of Variable Range Hopping in Hydrogenated Amorphous Silicon-Nickel Alloys

Journal of Modern Physics, 2012

On the insulating side of the metal-insulator transition (MIT), the study of the effect of low Te... more On the insulating side of the metal-insulator transition (MIT), the study of the effect of low Temperatures T on the electrical transport in amorphous silicon-nickel alloys a-Si 1-y Ni y :H exhibits that the electrical conductivity follows, at the beginning, the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T −1/2. This behaviour showed that long range electron-electron interaction reduces the Density of State of carriers (DOS) at the Fermi level and creates the Coulomb gap (CG). For T higher than a critical value of temperature T C , we obtained the Mott Variable Range Hopping regime with T −1/4 , indicating that the DOS becomes almost constant in the vicinity of the Fermi level. The critical temperature T C decreases with nickel content in the alloys.

Research paper thumbnail of Density inhomogeneity driven metal–insulator transition in 2D p-GaAs

Physica E: Low-dimensional Systems and Nanostructures, 2013

Research paper thumbnail of Density inhomogeneity driven metal–insulator transition in 2D p-GaAs

Physica E: Low-dimensional Systems and Nanostructures, 2013

Research paper thumbnail of Density inhomogeneity driven metal–insulator transition in 2D p-GaAs

Physica E: Low-dimensional Systems and Nanostructures, 2013

Research paper thumbnail of Analysis of thermoelectric effect of wet spun graphene fiber composites

International Journal of Low-Carbon Technologies

In this manuscript, we have theoretically reanalyzed data prepared and already published by Forou... more In this manuscript, we have theoretically reanalyzed data prepared and already published by Foroughi et al.[1]. These data concern the thermal energy dependence of the electrical conductivity of the samples: Graphene fiber, graphene/Poly(3,4-ethylenedioxythiophene)(graphene/PEDOT), graphene/ carbone nanotube(graphene/CNT) and graphene/carbone nonotube/Poly(3,4-ethylenedioxythiophene)(graphene/CNT/PEDOT) composite fibers. We investigate the behavior of the thermal conductivity for these four samples. These samples are considered as thermoelectric materials or green energy conversion materials using the Seebeck effect to transform heat into electrical energy and vice versa. In this context, the optimization of the ZT merit factor remains a challenge for the scientific community. The objective of this investigation is to evaluate and characterize the thermoelectric efficiency of the above-mentioned samples. We confront the experimental data with the existing theoretical models. The the...

Research paper thumbnail of Contribution of weak localization and electron-electron interaction, in corrective term “mT1/2” of the metallic conductivity in n-type SiAs

We present measurements of the electrical conductivity of barely metallic n-type SiAs that are dr... more We present measurements of the electrical conductivity of barely metallic n-type SiAs that are driven to the metal-insulator transition (MIT) by impurity concentration. The experiments were carried out at low temperature in the range (3.48 - 0.00044 K) and with impurity concentrations up to . On the metallic side of the MIT, the electrical conductivity is found to behave likedown to 0.44 mK. Physical explanation to the temperature dependence of the conductivity is given in metallic side of the MIT using a competition between two effects involved in the mechanisms of conduction, like electron-electron interaction effect, and weak localization effect.

Research paper thumbnail of Positive Magnetoresistance in Hydrogenated Amorphous Alloys Silicon Nickel a-Si1–yNiy:H at Very Low Temperature with Magnetic Field

We present results of an experimental study of magnetoresistance phenomenon in an amorphous silic... more We present results of an experimental study of magnetoresistance phenomenon in an amorphous silicon-nickel alloys a-Si1–yNiy:H (where y = 0.23) on the insulating side of the metal-insulator transition (MIT) in presence of magnetic field up to 4.5 T and at very low temperature. The electrical resistivity is found to follow the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T–1/2. This behaviour indicates the existence of the Coulomb gap (CG) near the Fermi level.

Research paper thumbnail of Negative Magnetoresistance Behaviour and Variable Range Hopping Conduction in Insulating NbSi Amorphous Alloys at Very Low Temperature with Magnetic Field

We present results of an experimental study of magnetoresistance (MR) in insulating NbSi amorphou... more We present results of an experimental study of magnetoresistance (MR) in insulating NbSi amorphous alloys sample showing Variable Range Hopping (VRH) conductivity. The MR is found to be negative in a wide range of low tem-perature (4.2- 20 K) and in the range of moderate magnetic fields (0- 4 T). We made tentative analysis using three theoretical models which are the model of quantum interference, the model of Zeeman effect and the model of localized magnetic moments

Research paper thumbnail of Analysis of the dielectric function of aluminum (Al) in bulk and nanometric states

Molecular Crystals and Liquid Crystals, 2020

We model the dielectric function of aluminum (Al). The modeling has been performed on Al in bulk ... more We model the dielectric function of aluminum (Al). The modeling has been performed on Al in bulk and nanometric states. First, we will model the experimental measurements of the dielectric constant as a function of the pulsation ω by appropriate mathematical functions in an explicit way. In the second part, we will highlight the contributions due to intraband and interband electronic transitions. In the last part, we model the dielectric constant of this metal in the nanometric state using several complex theoretical models such as the Drude Lorentz theory and the Drude two-point critical model. We shall comment on which model fits the experimental dielectric function best.

Research paper thumbnail of Modeling the Bulk and Nanometric Dielectric Functions of Au and Ag

Magnetic Skyrmions

In this work, we model the dielectric functions of gold (Au) and silver (Ag) which are typically ... more In this work, we model the dielectric functions of gold (Au) and silver (Ag) which are typically used in photonics and plasmonics. The modeling has been performed on Au and Ag in bulk and in nanometric states. The dielectric function is presented as a complex number with a real part and an imaginary part. First, we will model the experimental measurements of the dielectric constant as a function of the pulsation ω by appropriate mathematical functions in an explicit way. In the second part we will highlight the contributions to the dielectric constant value due to intraband and interband electronic transitions. In the last part of this work we model the dielectric constant of these metals in the nanometric state using several complex theoretical models such as the Drude Lorentz theory, the Drude two-point critical model, and the Drude three-point critical model. We shall comment on which model fits the experimental dielectric function best over a range of pulsation.

Research paper thumbnail of Efros–Shklovskii hopping in the electronic transport in 2D p-GaAs

Lithuanian Journal of Physics

We have investigated the resistivity of a 2D hole system in GaAs in the temperature range 200 mK ... more We have investigated the resistivity of a 2D hole system in GaAs in the temperature range 200 mK < T < 800 mK at zero magnetic field and low hole densities when the system is near the metal–insulator transition in the insulating side. We have found that the resistivity follows the Efros–Shklovskii variable range hopping (ES-VRH) law, this behaviour is consistent with the existence of a Coulomb gap. The resistivity scales with temperature and the prefactor has been found independent of temperature and density, thus confirming the dominance of hole–hole interaction.

Research paper thumbnail of Negative magnetoresistance behaviour and variable range hopping conduction in insulating NbSi amorphous alloys at very low temperature with magnetic field

Physical Chemistry of Interfaces and Nanomaterials XI, 2012

We present results of an experimental study of magnetoresistance (MR) in insulating NbSi amorphou... more We present results of an experimental study of magnetoresistance (MR) in insulating NbSi amorphous alloys sample showing Variable Range Hopping (VRH) conductivity. The MR is found to be negative in a wide range of low temperature (4.2-20 K) and in the range of moderate magnetic fields (0-4 T). We made tentative analysis using three theoretical models which are the model of quantum interference, the model of Zeeman effect and the model of localized magnetic moments

Research paper thumbnail of Variable range hopping conduction in insulating n-type InSb semiconductor

Physical Chemistry of Interfaces and Nanomaterials XI, 2012

Research paper thumbnail of Positive magnetoresistance in hydrogenated amorphous alloys silicon nickel a- Si1-yNiy:H at very low temperature with magnetic field

Physical Chemistry of Interfaces and Nanomaterials XI, 2012

We present results of an experimental study of magnetoresistance phenomenon in an amorphous silic... more We present results of an experimental study of magnetoresistance phenomenon in an amorphous silicon-nickel alloys a-Si 1-y Ni y :H (where y = 0.23) on the insulating side of the metal-insulator transition (MIT) in presence of magnetic field up to 4.5 T and at very low temperature. The electrical resistivity is found to follow the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T-1/2. This behaviour indicates the existence of the Coulomb gap (CG) near the Fermi level.

Research paper thumbnail of Study of electrical conductivity and scale theory in metallic n-type GeSb

Physical Chemistry of Interfaces and Nanomaterials XI, 2012

Research paper thumbnail of Variable Range Hopping in Hydrogenated Amorphous Silicon-Nickel Alloys

Journal of Modern Physics, 2012

On the insulating side of the metal-insulator transition (MIT), the study of the effect of low Te... more On the insulating side of the metal-insulator transition (MIT), the study of the effect of low Temperatures T on the electrical transport in amorphous silicon-nickel alloys a-Si 1-y Ni y :H exhibits that the electrical conductivity follows, at the beginning, the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T −1/2. This behaviour showed that long range electron-electron interaction reduces the Density of State of carriers (DOS) at the Fermi level and creates the Coulomb gap (CG). For T higher than a critical value of temperature T C , we obtained the Mott Variable Range Hopping regime with T −1/4 , indicating that the DOS becomes almost constant in the vicinity of the Fermi level. The critical temperature T C decreases with nickel content in the alloys.

Research paper thumbnail of Density inhomogeneity driven metal–insulator transition in 2D p-GaAs

Physica E: Low-dimensional Systems and Nanostructures, 2013

Research paper thumbnail of Density inhomogeneity driven metal–insulator transition in 2D p-GaAs

Physica E: Low-dimensional Systems and Nanostructures, 2013

Research paper thumbnail of Density inhomogeneity driven metal–insulator transition in 2D p-GaAs

Physica E: Low-dimensional Systems and Nanostructures, 2013