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Bahri Rezig

Ecole Nationale d'Ingénieurs de Tunis (ENIT), Industrial Engineering, Faculty Member

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Researcher in New materials for photo voltaics applications. Recent interest and work on National Innovation EcoSystems (IES) and contextualization in DC. Transfrontiers IES design and implémentation Project.

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Northwestern University

Rajaram S . Mane

Swami Ramanand Teerth Marathwada University, Nanded

Luis E Sansores Cuevas

Pradip Basnet, Ph.D.

Georgia Institute of Technology

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Papers by Bahri Rezig

Photo-induced junction behaviour of light-degraded CdSCu2S solar cells

Solar Cells, 1985

An electro-optical study has been carried out on as-made and degraded Cu2S/CdS solar cells. Doubl... more An electro-optical study has been carried out on as-made and degraded Cu2S/CdS solar cells. Doubly excited photoresponse, Isc and Vo¢ spectral dispersion measurements have been analysed. It appears that the photoinduced junction behaviour is almost entirely governed by the light modulation of the CdS space charge parameters. For all cells, one deep impurity level was found in the CdS band gap near 2.1 eV below the conduction band. A second deeper level located at 1.38 eV above the valence band is exhibited by light-degraded and uncontacted cells. It is responsible for the drastic quenching effect observed in the IR spectral region. Also, this level is associated with a photo-adsorbed impurity during illuminated degradation tests. Complementary photocapacitance analysis reported elsewhere showed a third rather less well resolved level at 1.65 eV below the conduction band and confirmed that both the 2.1 and 1.65 eV levels are related to as-made CdS base material probably arising from CdS distortion and/or originating copper "intrusions".

Optical and structural behaviour of CuxS grown from copper, indium doped CdS sprayed thin films

Solar Energy Materials, 1984

Thin CuxS layers are obtained by partial or complete dipping of doped sprayed CdS films. The CdS ... more Thin CuxS layers are obtained by partial or complete dipping of doped sprayed CdS films. The CdS doping studies were made with the following impurities: copper, indium or copper + indium, with different concentrations. The effects of the doping on the structural and optical properties of CuxS layers are presented here. It is shown that, unlike indium, copper above a few ppm induces degradation of almost all chemical and optical characteristics of the CuxS layer by introducing serious damages on crystallinity of the CdS layer. By introducing indium with copper, the former tends to moderate this drastic effect and to bring the optical and structural properties of couple doped films to acceptable levels.

Fractal growth by local sensitive epidemic model (LSEM) simulating the internal feeding systems (IFS)

Physica A: Statistical Mechanics and its Applications, 2001

The fractal systems may be classified into two families which are distinguishable by a different ... more The fractal systems may be classified into two families which are distinguishable by a different nutrient feeding during their growth process. For the internal feeding systems (IFS), the source is directly connected to the growing interface, while for the external feeding systems (EFS) it is placed far away so that the released particles have to execute random walks before adhering to the aggregate. A generalized model, nicknamed local sensitive epidemic model (LSEM) is developed to unify the main models simulating the growth of the IFSystems, by combining all their growth parameters (GP) and growth rules (GR). This model considers in addition: (i) a particle interaction extended to the kth neighbour, which may be attractive or repulsive; (ii) a continuous updating of the local characteristics of the surrounding medium; and (iii) an aggregate relaxation which tends to optimize the total energy during or after the growth process. The coupled effects of all these parameters allow one to simulate the main fractal phases observed experimentally, and to discuss the conditions under which they may be obtained as well as their different morphological transitions.

Optical Properties of the Quasi-Periodic One-Dimensional Genarilized Multilayer Fibonacci Structures

Progress In Electromagnetics Research, 2006

Page 1. Progress In Electromagnetics Research, PIER 59, 6983, 2006 OPTICAL PROPERTIES OF THE QUA... more

Effect of the substrate temperature on the properties of the RF sputtered TiO2 thin films

Physica Status Solidi (c), 2010

Fabrication and characterization of CuAlO2 transparent thin films prepared by spray technique

Materials Science and Engineering: B, 2005

CITATIONS 2 READS 75 4 authors, including:

A new model of very high efficiency buried emitter silicon solar cell

Solar Energy Materials and Solar Cells, 1997

In this work, we report a new model of symmetrical silicon solar structure where the emitter is b... more

Influence of Deposition Time on Properties of the RF Sputtered TiO<sub>2</sub> Thin Films

Materials Science Forum, 2008

Characterization of n-ZnO/p-Si films grown by magnetron sputtering

Superlattices and Microstructures, 2006

ZnO films were deposited by RF magnetron sputtering on single p-Si substrates to form n-ZnO/p-Si ... more ZnO films were deposited by RF magnetron sputtering on single p-Si substrates to form n-ZnO/p-Si heterojunctions. Various substrate temperatures of 25, 100, 200, 300 and 400 ∘C were used.The electrical junction properties were characterized by current–voltage (I–V) and capacitance–voltage (C–V) methods.Calculations of the barrier height from classical 1/C2–V characterizations and from the I–V in dark conditions indicate merely the same values

Effect of RF power on the properties of magnetron sputtered ZnO:Al thin films deposited at room temperature

Materials Science Forum, 2010

... We attribute the slight increase in Eg with RF power for our ZnO:Al films to the Burstein–Mos... more

Optical constants of Na-doped CuInS2 thin films

Materials Letters, 2006

Optical properties of sodium-doped CuInS 2 thin films grown by the single-source thermal evaporat... more Optical properties of sodium-doped CuInS 2 thin films grown by the single-source thermal evaporation method have been studied. The optical constants of the deposited films were obtained from the analysis of the experimental recorded transmission and reflectance spectral data over the wavelength range 300 -1800 nm. It is observed that there is decrease in optical band gap with increase in sodium concentration. It has been found that the refractive index and extinction coefficient are dependent on the sodium concentration. The complex dielectric constants of CuInS 2 :Na films have been calculated in the investigated wavelength range. It was found that the refractive index dispersion data obeyed the single oscillator of the Wemple -Di Domenico model, from which the dispersion parameters and the high-frequency dielectric constant were determined. The electric free carrier susceptibility and the carrier concentration on the effective mass ratio were estimated according to the model of Spitzer and Fan. D

A Dielectric Chirped Layered Mirror for Optical Telecommunication Wavelengths

Optical Review, 2007

Studies on the properties of sputter-deposited Al-doped ZnO films

Superlattices and Microstructures, 2008

ABSTRACT ZnO is a well known material; however, the research interest in this material is still h... more ABSTRACT ZnO is a well known material; however, the research interest in this material is still high enough because ZnO is one of the materials with the most potential for optoelectronics due to its promising properties of high conductivity as well as good transparency. In this work, aluminum doped zinc oxide films (ZnO:Al) were deposited by RF magnetron sputtering on glass and silicon substrates with different deposition times of 2, 3 and 4 h. The aim of this work is the study of the deposition time effect on the properties of ZnO:Al films. It is shown that films grow with the hexagonal c-axis perpendicular to the substrate surface. The morphological characteristics show a granular and homogenous surface and the cristallinity of the films is enhanced with increased deposition time. The deposited films show good optical transmittance (80%–90%) in the visible and near infrared spectrum. The calculated band gap is about 3.3 eV. The electrical ZnO:Al/Si(p) junction properties were investigated using the Capacitance–Voltage (C–V) dependence. Calculations of the built-in potential from classical 1/C2–V characterization give values between 0.54 and 0.71 V.This work shows how the variation of deposition time allows the control of structural, electrical and optical properties of the films.

Theoretical possibilities of InxGa1−xN tandem PV structures

Solar Energy Materials and Solar Cells, 2005

We designed a model of InxGa1-xN tandem structure made of N successive p-n junctions going from t... more We designed a model of InxGa1-xN tandem structure made of N successive p-n junctions going from three cells for the less sophisticated structure to seven cells for the most sophisticated. We simulated the photocurrent and the open circuit voltage of each structure under AM 1.5 illumination in goal to optimize the number of successive cells forming one structure. For each

Structural and optical properties of sulfur-annealed CuInS2 thin films

Solar Energy Materials and Solar Cells, 1999

thin "lms were deposited by single source vacuum thermal evaporation method on substrates submitt... more thin "lms were deposited by single source vacuum thermal evaporation method on substrates submitted to longitudinal thermal gradient. Some of these "lms were annealed in sulfur atmosphere and converted into CuInS homogenous layers. Both of the as-deposited and sulfurated "lms were characterized by X-ray di!raction, optical transmission and re#ection measurements. The optical band gap of "lms after sulfurization was 1.50 eV which is near the optimum value for photovoltaic energy conversion.

Metrological characteristics of ZNO oxygen sensor at room temperature

Sensors and Actuators B: Chemical, 2004

ZnO films were deposited by RF magnetron sputtering in an argon atmosphere, on glass and p-silico... more ZnO films were deposited by RF magnetron sputtering in an argon atmosphere, on glass and p-silicon substrates. The morphological characteristics of the as deposited films were investigated. Scanning electron microscopy (SEM) showed that these films were granular and homogeneous. The study of gas sensing properties of the samples was carried out through the change in resistivity due to the adsorption and desorption of the atmospheric oxygen. It was shown that the gas sensitive properties are strongly correlated with the fabricated microstructure which depends on the deposition parameters and on the substrate nature. Thus, ZnO films are very promising materials for the application as gas sensor at room temperature through their electrical resistance change on different atmospheres.

Studies of structural and optical properties of Cu-In-O thin films

physica status solidi (a), 2008

The user has requested enhancement of the downloaded file. All in-text references underlined in b... more

Nanocolumnar CuInS2 thin films by glancing angle deposition

Physica E: Low-dimensional Systems and Nanostructures, 2008

Copper indium disulfide was deposited on native glass substrates using glancing angle deposition ... more Copper indium disulfide was deposited on native glass substrates using glancing angle deposition with and without substrate rotation. The growth mechanism and film morphology are explored in detail. Due to the shadowing effect, the glancing angle deposition (GLAD) technique can produce nanorods tilted toward the incident deposition flux. During depositions, the substrate temperature was maintained at 200°C. The evaporated atoms

Effect of annealing on optical and structural properties of ZnS/MnS and MnS/ZnS superlattices thin films for solar energy application

Optik - International Journal for Light and Electron Optics, 2014

ABSTRACT

Effect of substrate thermal gradient on as-grown CuInS2 properties

Materials Research Bulletin, 1997

Copper indium disulflde thin films were deposited by vacuum thermal evaporation method. The inter... more Copper indium disulflde thin films were deposited by vacuum thermal evaporation method. The interest of this study is focused on the effects of substrate heating conditions on the layer growth and properties. It was found that a longitudinal thermal gradient (LTG), even small, induces drastical changes in optical properties of the layers which behave as a highly absorbing material. Crystallized resistive and highly absorbing as-made layers were studied in comparison with "standard" CuInS2 samples (conductive heating at 250°C). Electrical, structural, and optical analysis showed that the involved prominent property (i.e., opacity) seems to be a volume effect occurring during growth stage and is clearly correlated to LTG conditions. On the other hand, thermal cycling in vacuum in the 293-573 K range did not show any electrical disturbance as exhibited in the "standard' Cllh& CZISC. CD 1597 Elsevier Science Ltd

Photo-induced junction behaviour of light-degraded CdSCu2S solar cells

Solar Cells, 1985

An electro-optical study has been carried out on as-made and degraded Cu2S/CdS solar cells. Doubl... more An electro-optical study has been carried out on as-made and degraded Cu2S/CdS solar cells. Doubly excited photoresponse, Isc and Vo¢ spectral dispersion measurements have been analysed. It appears that the photoinduced junction behaviour is almost entirely governed by the light modulation of the CdS space charge parameters. For all cells, one deep impurity level was found in the CdS band gap near 2.1 eV below the conduction band. A second deeper level located at 1.38 eV above the valence band is exhibited by light-degraded and uncontacted cells. It is responsible for the drastic quenching effect observed in the IR spectral region. Also, this level is associated with a photo-adsorbed impurity during illuminated degradation tests. Complementary photocapacitance analysis reported elsewhere showed a third rather less well resolved level at 1.65 eV below the conduction band and confirmed that both the 2.1 and 1.65 eV levels are related to as-made CdS base material probably arising from CdS distortion and/or originating copper "intrusions".

Optical and structural behaviour of CuxS grown from copper, indium doped CdS sprayed thin films

Solar Energy Materials, 1984

Thin CuxS layers are obtained by partial or complete dipping of doped sprayed CdS films. The CdS ... more Thin CuxS layers are obtained by partial or complete dipping of doped sprayed CdS films. The CdS doping studies were made with the following impurities: copper, indium or copper + indium, with different concentrations. The effects of the doping on the structural and optical properties of CuxS layers are presented here. It is shown that, unlike indium, copper above a few ppm induces degradation of almost all chemical and optical characteristics of the CuxS layer by introducing serious damages on crystallinity of the CdS layer. By introducing indium with copper, the former tends to moderate this drastic effect and to bring the optical and structural properties of couple doped films to acceptable levels.

Fractal growth by local sensitive epidemic model (LSEM) simulating the internal feeding systems (IFS)

Physica A: Statistical Mechanics and its Applications, 2001

The fractal systems may be classified into two families which are distinguishable by a different ... more The fractal systems may be classified into two families which are distinguishable by a different nutrient feeding during their growth process. For the internal feeding systems (IFS), the source is directly connected to the growing interface, while for the external feeding systems (EFS) it is placed far away so that the released particles have to execute random walks before adhering to the aggregate. A generalized model, nicknamed local sensitive epidemic model (LSEM) is developed to unify the main models simulating the growth of the IFSystems, by combining all their growth parameters (GP) and growth rules (GR). This model considers in addition: (i) a particle interaction extended to the kth neighbour, which may be attractive or repulsive; (ii) a continuous updating of the local characteristics of the surrounding medium; and (iii) an aggregate relaxation which tends to optimize the total energy during or after the growth process. The coupled effects of all these parameters allow one to simulate the main fractal phases observed experimentally, and to discuss the conditions under which they may be obtained as well as their different morphological transitions.

Optical Properties of the Quasi-Periodic One-Dimensional Genarilized Multilayer Fibonacci Structures

Progress In Electromagnetics Research, 2006

Page 1. Progress In Electromagnetics Research, PIER 59, 6983, 2006 OPTICAL PROPERTIES OF THE QUA... more

Effect of the substrate temperature on the properties of the RF sputtered TiO2 thin films

Physica Status Solidi (c), 2010

Fabrication and characterization of CuAlO2 transparent thin films prepared by spray technique

Materials Science and Engineering: B, 2005

CITATIONS 2 READS 75 4 authors, including:

A new model of very high efficiency buried emitter silicon solar cell

Solar Energy Materials and Solar Cells, 1997

In this work, we report a new model of symmetrical silicon solar structure where the emitter is b... more

Influence of Deposition Time on Properties of the RF Sputtered TiO<sub>2</sub> Thin Films

Materials Science Forum, 2008

Characterization of n-ZnO/p-Si films grown by magnetron sputtering

Superlattices and Microstructures, 2006

ZnO films were deposited by RF magnetron sputtering on single p-Si substrates to form n-ZnO/p-Si ... more ZnO films were deposited by RF magnetron sputtering on single p-Si substrates to form n-ZnO/p-Si heterojunctions. Various substrate temperatures of 25, 100, 200, 300 and 400 ∘C were used.The electrical junction properties were characterized by current–voltage (I–V) and capacitance–voltage (C–V) methods.Calculations of the barrier height from classical 1/C2–V characterizations and from the I–V in dark conditions indicate merely the same values

Effect of RF power on the properties of magnetron sputtered ZnO:Al thin films deposited at room temperature

Materials Science Forum, 2010

... We attribute the slight increase in Eg with RF power for our ZnO:Al films to the Burstein–Mos... more

Optical constants of Na-doped CuInS2 thin films

Materials Letters, 2006

Optical properties of sodium-doped CuInS 2 thin films grown by the single-source thermal evaporat... more Optical properties of sodium-doped CuInS 2 thin films grown by the single-source thermal evaporation method have been studied. The optical constants of the deposited films were obtained from the analysis of the experimental recorded transmission and reflectance spectral data over the wavelength range 300 -1800 nm. It is observed that there is decrease in optical band gap with increase in sodium concentration. It has been found that the refractive index and extinction coefficient are dependent on the sodium concentration. The complex dielectric constants of CuInS 2 :Na films have been calculated in the investigated wavelength range. It was found that the refractive index dispersion data obeyed the single oscillator of the Wemple -Di Domenico model, from which the dispersion parameters and the high-frequency dielectric constant were determined. The electric free carrier susceptibility and the carrier concentration on the effective mass ratio were estimated according to the model of Spitzer and Fan. D

A Dielectric Chirped Layered Mirror for Optical Telecommunication Wavelengths

Optical Review, 2007

Studies on the properties of sputter-deposited Al-doped ZnO films

Superlattices and Microstructures, 2008

ABSTRACT ZnO is a well known material; however, the research interest in this material is still h... more ABSTRACT ZnO is a well known material; however, the research interest in this material is still high enough because ZnO is one of the materials with the most potential for optoelectronics due to its promising properties of high conductivity as well as good transparency. In this work, aluminum doped zinc oxide films (ZnO:Al) were deposited by RF magnetron sputtering on glass and silicon substrates with different deposition times of 2, 3 and 4 h. The aim of this work is the study of the deposition time effect on the properties of ZnO:Al films. It is shown that films grow with the hexagonal c-axis perpendicular to the substrate surface. The morphological characteristics show a granular and homogenous surface and the cristallinity of the films is enhanced with increased deposition time. The deposited films show good optical transmittance (80%–90%) in the visible and near infrared spectrum. The calculated band gap is about 3.3 eV. The electrical ZnO:Al/Si(p) junction properties were investigated using the Capacitance–Voltage (C–V) dependence. Calculations of the built-in potential from classical 1/C2–V characterization give values between 0.54 and 0.71 V.This work shows how the variation of deposition time allows the control of structural, electrical and optical properties of the films.

Theoretical possibilities of InxGa1−xN tandem PV structures

Solar Energy Materials and Solar Cells, 2005

We designed a model of InxGa1-xN tandem structure made of N successive p-n junctions going from t... more We designed a model of InxGa1-xN tandem structure made of N successive p-n junctions going from three cells for the less sophisticated structure to seven cells for the most sophisticated. We simulated the photocurrent and the open circuit voltage of each structure under AM 1.5 illumination in goal to optimize the number of successive cells forming one structure. For each

Structural and optical properties of sulfur-annealed CuInS2 thin films

Solar Energy Materials and Solar Cells, 1999

thin "lms were deposited by single source vacuum thermal evaporation method on substrates submitt... more thin "lms were deposited by single source vacuum thermal evaporation method on substrates submitted to longitudinal thermal gradient. Some of these "lms were annealed in sulfur atmosphere and converted into CuInS homogenous layers. Both of the as-deposited and sulfurated "lms were characterized by X-ray di!raction, optical transmission and re#ection measurements. The optical band gap of "lms after sulfurization was 1.50 eV which is near the optimum value for photovoltaic energy conversion.

Metrological characteristics of ZNO oxygen sensor at room temperature

Sensors and Actuators B: Chemical, 2004

ZnO films were deposited by RF magnetron sputtering in an argon atmosphere, on glass and p-silico... more ZnO films were deposited by RF magnetron sputtering in an argon atmosphere, on glass and p-silicon substrates. The morphological characteristics of the as deposited films were investigated. Scanning electron microscopy (SEM) showed that these films were granular and homogeneous. The study of gas sensing properties of the samples was carried out through the change in resistivity due to the adsorption and desorption of the atmospheric oxygen. It was shown that the gas sensitive properties are strongly correlated with the fabricated microstructure which depends on the deposition parameters and on the substrate nature. Thus, ZnO films are very promising materials for the application as gas sensor at room temperature through their electrical resistance change on different atmospheres.

Studies of structural and optical properties of Cu-In-O thin films

physica status solidi (a), 2008

The user has requested enhancement of the downloaded file. All in-text references underlined in b... more

Nanocolumnar CuInS2 thin films by glancing angle deposition

Physica E: Low-dimensional Systems and Nanostructures, 2008

Copper indium disulfide was deposited on native glass substrates using glancing angle deposition ... more Copper indium disulfide was deposited on native glass substrates using glancing angle deposition with and without substrate rotation. The growth mechanism and film morphology are explored in detail. Due to the shadowing effect, the glancing angle deposition (GLAD) technique can produce nanorods tilted toward the incident deposition flux. During depositions, the substrate temperature was maintained at 200°C. The evaporated atoms

Effect of annealing on optical and structural properties of ZnS/MnS and MnS/ZnS superlattices thin films for solar energy application

Optik - International Journal for Light and Electron Optics, 2014

ABSTRACT

Effect of substrate thermal gradient on as-grown CuInS2 properties

Materials Research Bulletin, 1997

Copper indium disulflde thin films were deposited by vacuum thermal evaporation method. The inter... more Copper indium disulflde thin films were deposited by vacuum thermal evaporation method. The interest of this study is focused on the effects of substrate heating conditions on the layer growth and properties. It was found that a longitudinal thermal gradient (LTG), even small, induces drastical changes in optical properties of the layers which behave as a highly absorbing material. Crystallized resistive and highly absorbing as-made layers were studied in comparison with "standard" CuInS2 samples (conductive heating at 250°C). Electrical, structural, and optical analysis showed that the involved prominent property (i.e., opacity) seems to be a volume effect occurring during growth stage and is clearly correlated to LTG conditions. On the other hand, thermal cycling in vacuum in the 293-573 K range did not show any electrical disturbance as exhibited in the "standard' Cllh& CZISC. CD 1597 Elsevier Science Ltd