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International audience; This effort is founded on the modeling and simulation of the GaAsPN/GaP quantum dot (QD) solar cell. This quaternary alloy is one of the III-V semiconductors, which gained importance in the recent years for optoelectronic applications. This importance comes from the fact that the quaternary GaAsPN can be a well-grown lattice matched to GaP and Si substrates and to the bandgap that can be decreased drastically with the incorporation of nitrogen and arsenic into GaP, improving consequently the absorption and the wavelengths near the red part. These qualities make GaAsPN a good candidate for the growth on the Si substrate and low-cost solar cell fabrication. The optical properties of GaAsPN/GaP QDs, such as strain, critical thickness, bandgap energy, the external quantum efficiency, and absorption coefficient, have been reported. The heterostructures consist of GaAs0.18P0.814N0.006 QDs separated by GaP barrier layers. The width and thickness of QDs are about 5 and 5 nm, respectively. Our results have been shown that 20 GaAs0.18P0.814N0.006/GaP QD layers produce a short-circuit current of about 3.55 mA/cm2 and an efficiency of about 7.5%. In addition, we will be able to extend the absorption edge of a GaP solar cell from 0.48 μm to 0.5 μm for the same QD number layers inserted. The temperature effect on efficiency is considered.

International audience; AbstractThe present study reports the impact of structural parameters on optoelectronic properties of InGasb/GaSb based quantum well structures (Qws). The laser diodes are designed to operate at 2.3 μm at 300 K. Numerical calculations of the emission wavelength, optical and modal gain of TE mode in InGaSb/GaSb laser diode structure have been carried out for various well material compositions, well thickness, number of quantum wells and temperature. The optical confinement factor and threshold current density are also simulated and reported. The calculations were performed using the 8-bands k.p model. For an injected carrier concentration of 1.56 × 1018 cm−3 at 300 K, peak gain value of the order of 1400 cm−1 is reached and a modal gain of 94 cm−1 can be obtained. A threshold current density around 3 kA/cm2, is expected to be obtained through optical losses of about 50 cm−1. The results show that InGaSb/GaSb quantum wells are appropriate for mid-infrared lasers operating at 300 K.

The objective of this work is to simulate and optimize the physical properties of the quaternary semiconductor InGaAsP deposited on InP substrate, in order to enhance the efficiency of photovoltaic cells through the optimization of the bandgap and the absorption coefficient. To this end, the impact of the Gallium and Phosphorus concentrations on the strain as well as on the bandgap energy were studied. We have found that the absorption coefficient increases with the strain to reach 4.4 × 104 cm−1, thus, the strain allows to provide additional flexibility on the structure of solar cells and makes the alloy InGaAsP/InP promising for the design of photovoltaic cells based on the quaternary InGaAsP compound.

The most well-known solar cells are made of semiconductors, mainly based on crystalline silicon (mono- or poly-crystalline). It consists in converting solar radiation into electricity. Generally, the solar cell device that can carry out this function is essentially a single PN junction with large surface. The most of solar cells on the market today are based on silicon crystal. Currently, multiple researches are in progress in order to realize cells with multi junctions, tandem, by connecting to the silicon cell, another cell based on a material with wide gap energy in order to obtain a better efficiency. In this paper, we studied the efficiency of a silicon solar cell by using TCAD—Silvaco tools. The silicon solar cell structure was defined using Athena 2D process simulator that permit to create the structure in order to study it and use it in predictive simulation. On the other hand, the electrical simulation was performed using Atlas simulator. After simulation, the final output parameters are Voc = 0.61 V, Jsc = 23.267 mA.cm−2, FF = 0.795 and 11.30% of efficiency.

This paper reviews some of the major initial results gained within the last few years towards a full optoelectronic silicon based integration platform. For that, the electrical properties of Si/GaAsP quantum dot solar cell (QDSC) are numerically studied and analyzed. By the studies of the effect of quantum dot (QD) layers inserted and phosphor content of GaAs 1-x P x on photovoltaic properties such as current density-voltage J-V and the external quantum efficiency (EQE), Our Si/GaAsP QDs exhibit high open-circuit voltage and quantum efficiency, then the Si p-i-n solar cell. These measurements also indicate that 20 layers of Si/GaAsP QD, provide an improvement from 2.78 % to 9.20% of efficiency. The results in this work show a realistic path towards a development of Si/GaAsP QDSC with a high efficiency than conventional semiconductor-based solar cells.

International audience; This paper reports simulations of gradual bandgap CIGS absorber and its impact on the characteristics of a solar cell. The bandgap of the CIGS absorber varies linearly and drops from Egmax (at the junction limit) to Egmin (in the vicinity of the rear contact).We introduce an effective absorption coefficient based on this variation. We will demonstrate that this gradual profile contributes to an improvement up to 171 mV of the open circuit voltage Voc of the cell that is linked to the modification of the internal electrical field distribution within the absorber. However, a joint reduction of 1.50 mA/cm2 of short circuit current density, Jsc, is observed. Overall, the conversion efficiency increases from 19.2%, for a uniform bandgap absorber structure, to 24.9% in that case of gradual bandgap. Additionally, we investigate the impact of absorber thickness and temperature on cell characteristics

The electrical properties of InAsP/Si quantum dot solar cell (QDSC) are numerically studied and analyzed in this paper. Many effects like number of quantum dot (QD) layers inserted and Arsenic content of InAs x P 1-x on photovoltaic properties such as current density-voltage J-V and the external quantum efficiency (EQE) are investigated. Our results have been shown that the optimal Arsenic content is 0.6. With 30 InAsP/Si QDs layers, relative enhancements of about 7% and 6.70% of short-circuit current and efficiency are achieved, respectively. Otherwise, the absorption range edge of low energy photons was extended from 1120 to 1200 nm. This reveals that introduction of QDs in the intrinsic region of p -i- n Silicon (Si) solar cell enhances significantly the device characteristics beyond what has been reported for conventional semiconductor-based solar cells.

In this work, the performance of solar cell based on CdS-n/Cu 2 ZnSnS 4 -p hetero-junction is numerically simulated. The aim of the study is to investigate the influence of thickness, defects density and bandgap energy of absorber layer CZTS and the thickness of the buffer layer CdS of the solar cell on electrical parameters J sc , V oc , FF and efficiency η of the cell. The results of our simulation allowed us to optimize the parameters above mentioned in order to get the best efficiency at the optimal band gap which corresponds to the maximum of the solar spectrum with optimal values of the electrical performances of the cell. This results lead to develop CZTS solar cells with high efficiency and low cost and give a help full indication for fabrication process.

In this aim, we were interested in the optimization and simulation of pin-In1−xGaxN structure and InGaN multi quantum well structures for photovoltaic applications. This ternary alloy which is an III–V semiconductor presents important characteristics especially its gap energy, thus, the increase of the photons absorption of wavelengths. It has been shown that the increase in indium concentration increases the current density Jsc and the maximum output power. In return, the Voc decreases consequently. For In0.50Ga0.50N structure we observed that the current density and the maximum power are respectively around 19.50 mA/cm2 and 27.50 mW/cm2 with a ratio of 21.65 mA/cm2. Also it is shown that the incorporation of the quantum well in the active region results in an increase of Jsc and Pmax but Voc remains unchanged. The incorporation of 50 quantum well structure in the In0.50Ga0.50N gives 22 mA/cm2 of the current density and 32 mW/cm2 of the maximum output power. The use of the structure based on In0.50Ga0.50N (MQW) induces an efficiency of 32%. We deduced that the relative efficiency is improved by 10.9%.

This work deals with the modeling and optimization of the CuInGaSe/CdS based structure for photovoltaic applications. We took into consideration the effect of the gallium concentration and the temperature on the strain, band gap energy, absorption and efficiency of the structure. It has been demonstrated that increasing the gallium concentration increases the ban gap energy, while increasing temperature decreases it. These two parameters vary the efficiency significantly. For x = 30% and T = 300 K, the band gap energy is equal to 1.15 eV with a deformation of 0.5% and efficiency around 20%. We have also found that at this value of the band gap energy the structure absorbs most of the incident photons. Then to achieve a reliable cell based on CuInGaSe/CdS it is adequate to find a compromise between the gallium concentration in the alloy, the temperature and the strain.

Our work is used to investigate the electrical proprieties of III-V MOSFET (Metal Oxide Semiconductor Field Effect Transistor) from an InP/InAs/InGaAs structure. This simulation is done using Silvaco TCAD tools. We solve the coupled Poisson-Schrodinger equation that gives the carriers concentration and their eigen state energies at each level. The fundamental equations are based on the conventional drift-diffusion model of charge transport with Fermi-Dirac statistics and electric field-dependent mobility model. We present the charge control in channel and the complete I-V characteristics of InP/InAs/InGaAs MOSFET. The results obtained show the output Id-\( \text{V}_{{\rm{ds}}} \) and the transfer Id-\( \text{V}_{{\rm{gs}}} \) characteristic with Lg = 50 nm and To x = 4 nm. Ion of 330 mA/mm and maximum transconductance Gm of 405 mS/mm were calculated at Vd = 0.05 V. The transfer and Gm characteristics of this structure are shown with \( \text{L}_{\rm{g}} \) of 150 nm and 100 nm respectively. Ion and \( {\text{G}}_{{\rm{m,}\hbox{max} }} \) reach to (270–280) mA/mm and (328–346) mS/mm respectively. It is found that the threshold voltage decreases as the channel length is reduced.

This work focuses on the modeling and optimization of a structure based on InGaP/InGaAs/InGaAsN/Ge for photovoltaic. In this study we took into consideration the concentration effect of alloys x (In) and y (N) on the strain, the bandgap, the absorption and structure efficiency. It has been shown that the concentration of indium varies the strain and the bandgap. These two parameters change considerably the yield. Also it optimized the effect of alloys on the total absorption of the structure. For a concentration of indium x = 0.40 and y = 0.03 we had a absorption coefficient which is equal to 2 × 10 6 cm −1 . We have found 50% efficiency for the multi-junction structure based on In 0.55 Ga 0.45 P/In 0.40 Ga 0.60 As/In 0.30 Ga 0.70 As 0.97 N 0.03 /Ge. To achieve a reliable high efficiency multi-junction structure, we just need to optimize the concentrations of different alloys.

In this work, we designed a two-dimensional BDJ model and used finite element method to compute the response photocurrent instead of analytic model used in previous studies. To take into consideration multiphysics aspects COMSOL is used to study the optical and electrical behaviour of a Buried Double Junction (BDJ) photodetector designed with CMOS technology, the optical study describes the propagation of electromagnetic waves through air, silicon dioxide and silicon layers, the semiconductor study gives us the photocurrent for the two buried junctions to an incident wavelength.

We performed modeling and simulation of copper indium gallium diselenide (CIGS) thin film solar cell. CIGS absorbers today have a typical thickness of about 1–2 µm. However, on the way toward mass production, it will be necessary to reduce the thickness even further. We investigated the influence of the alloy compositions \( {\text{x = }}\left[ {\text{Ga}} \right]/\left\{ {\left[ {\text{In}} \right] + \left[ {\text{Ga}} \right]} \right\} \), the CIGS absorbers thickness and the temperature. Optimal results are obtained with a thickness of about 2 µm and a temperature of 318 K. It was also shown that, the short-circuit current density (Jsc) decreases when the x composition increases. Very high Jsc of 40.72 mA/cm2 was obtained, when x = 0.2. In contrary, the open-circuit voltage (Voc), the fill factor (FF) and the efficiency \( (\eta ) \) of the solar cell are increasing with the increase of the x composition. An optimal efficiency of about 30.34% was obtained with x = 0.9. Moreover, a comparison with published data for the Cu(In,Ga)Se2 cells have shown an excellent agreement.

In this paper, the frequency response calculation and optimization of PIN photodiodes based on GaN/InGaN, suitable for photodetection at the wavelength of 633 nm, are presented. The calculations of the impulse as well as the frequency response are performed using the impulse method. The frequency response optimization is a result of optimizing the transport of photo-generated carriers in the absorbent layer of the photodiode, using a mixed depletion region rather than a single absorbing depletion region. Cut-off frequencies of about 82 GHz and 48 GHz have been obtained in the case of transparent layer thickness of 500 nm and 1000 nm, respectively. The aforementioned results represent a very good improvement.

This work reports on theoretical studies on the GaInNAs material properties (bandgap, lattice mismatch, absorption coefficient) as grown on GaAs substrate. The Band Anti-Crossing (BAC) k ⋅ p 8 × 8 model has been used to determine the influence of indium and nitrogen concentrations on the position of conduction and valence bands. The incorporation of nitrogen at a level lower than 5% causes the split of the conduction band. For indium and nitrogen concentrations of 38% and 3.5%, respectively, the strained bandgap energy is 0.70 eV and the absorption coefficient of indium and nitrogen-rich compounds increases significantly.

The electrical and optical properties of InAsP/Si quantum dot solar cell are numerically analyzed in this paper. We have investigated many effects like the number of quantum dot layers inserted, and Arsenic composition of InAs x P 1−x on the mains characteristics of a solar cell: Current-Voltage, and the External Quantum Efficiency EQE. It has been shown that Arsenic composition of 60% and 80% provide maximal short circuit current and efficiency and with 30 InAsP/Si quantum dot layers, a relatives enhancements of about 7.02 % and 6.68 % of short-circuit current and efficiency are achieved respectively. Otherwise, the absorption range edge of photons with low energy extended from 1120 to 1200 nm. This reveals that introduction of QDs in the intrinsic region of Si p-i-n structures enhances significantly the device characteristics beyond what has been thus far reported for conventional semiconductor-based solar cells.

This work concerns the study and the simulation of a structure containing II-VI semiconductor for photovoltaic application. We studied the influence of the zinc concentration on the various parameters of the alloy Cd1-xZnxTe epitaxied on a CdTe substrate. Indeed, the insertion of zinc increases the band gap of the alloy, which is not ideal to absorb the maximum of the solar spectrum, but for low concentrations of zinc the Cd1-xZnxTe ternary material becomes attractive in the photovoltaic field. We have shown that for a Zinc composition (x) = 5%, the band gap is 1.52 eV. And if x = 20%, the gap is 1.62 eV.Our simulation studies have demonstrated that by an introduction of a specific Zinc concentration, we successfully simulated the achieving of 19% efficiency for solar devices.

In this work, we were interested about the study of modeling and simulation of a structure based on In1−xGaxN/GaN for photovoltaic applications. This ternary alloy who is an III-V semiconductor presents important characteristics especially its bandgap energy, thus the enhancement of the absorption of photons with wavelengths near to red. We had also studied a different parameters characterized the solar cell which served us to calculate the efficiency of photovoltaic conversion. For the In0.35Ga0.65N/GaN structure, we obtained efficiency around 23%. This study of structures allowed us to fabricate structures for solar cells based on multi-junction.

In this paper we present the optimization of photoswitches constituted of a coplanar line introducing interdigitated MSM photodetectors in the central strip. The reflection and the transmission coefficients are studied with the aim of highlighting the influence of different geometrical parameters on the photoswitch microwave behavior. In pursuance of improving the performances, new topologies of coplanar lines introducing tapers of linear shapes, as well as tightening of ground planes around the central strip are proposed and studied. The outcomes showed that it is possible to achieve high insulation (−52.3 dB) at the Off state. As for as the On/Off ratio is concerned, a value of 48.8 dB is reached.

The aim of this work is to model the properties of GaInAsNSb/GaAs compressively strained structures. Indeed, Ga1−xInxAs1−y−zNySbz has been found to be a potentially superior material to GaInAsN for long wavelength laser dedicated to optical fiber communications. Furthermore, this material can be grown on GaAs substrate while having a bandgap smaller than that of GaInNAs. The influence of nitrogen and antimony on the bandgap and the transition energy is explored. Also, the effect of these two elements on the optical gain and threshold current density is investigated. For example, a structure composed of one 7.5 nm thick quantum well of material with In=30%, N=3.5%, Sb=1% composition exhibits a threshold current density of 339.8 A/cm2 and an emission wavelength of 1.5365 μm (at T=300 K). It can be shown that increasing the concentration of indium to 35% with a concentration of nitrogen and antimony, of 2.5% and 1%, respectively, results in a decrease of the threshold current density down to 253.7 A/cm2 for a two well structure. Same structure incorporating five wells shows a threshold current density as low as 221.4 A/cm2 for T=300 K, which agrees well with the reported experimental results.

In this paper we have studied strained structures wells based on GaInAsSb over GaSb substrate. The GaSb substrates allow the mesh accordability with the GaInAsSb solid solution in the range 1.7–3.5 μm. The conduction band and valence discontinuities are evaluated. A Basic source-detector direct transition has been demonstrated at 2–3 μ m. The III-V based GaSb components have many applications in optical fiber links, radar transmissions through atmospheric windows or air detection and spectroscopic analysis of the gases. From this structure it is possible to make semiconductor lasers operating continuously at room temperature, low non-cooled detectors.

The objective is to exploit the properties of the GaInNAs/GaAs alloy compressive strain structure to design a laser diode likely to meet the needs of optical communications. Modelling concerns mainly the study of the potentialities of thermal stability and dynamic response offered by these new techniques of electric and optical confinement. Band structure is modelled and typical quantum well properties are illustrated. A thorough study of the structural parameters is undertaken to take into account from the design criteria the temperature sensitivity. Minimising the Auger coefficient in the order of 10^-^2^9cm^6/s appears to allow achieving efficient laser diodes production.

In this paper, we study the effect of the incorporation of nitrogen in strained GaInAs quantum well structures. We evaluate the influence of nitrogen on the conduction band energy by using the band anticrossing model. The incorporation of nitrogen appears to decrease the bandgap energy and increase the emission wavelength. The reduction of energy is due to the interaction of the energy of the conduction band with the level of nitrogen and more the concentration of nitrogen increases, more the energy of the band gap decreases. On the other hand, the emission wavelength increases, the advantage of the incorporation of nitrogen in such structures is to vary the wavelength between 0.980 and [email protected] while exploiting of course the composition of gallium, composition of nitrogen and the thickness of the quantum well. Less temperature insensitive devices are so intended to be fabricated.

In this work, we prepared aluminum-doped (Al) zinc oxide (ZnO) thin films using the sol-gel method, glass substrates have been used with zinc acetate as cations source and 2-methoxiethanol as solvent. The obtained experimental results show that the ZnO deposited films are relatively uniform. Optical measurements demonstrate that the deposited ZnO layers have a band gap of 3.26 eV which is close to that of the monocrystalline ZnO, about 3.3 eV. It was found that the roughness decreases by increasing the dopants concentration. Whatever the used substrate, transmission was observed between 75% and 99% for films deposited on ZnO:Al. Robust solar cells can be performed using from this study.