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In this work we study and optimize the single solar cell efficiency of GaN x As 1-x-y Sb y and Ga 1-x In x N y As 1-y deposed on GaAs. The solar cells are simulated, in the aim to find the best concentration of nitrogen and antimony for GaN x As 1-x-y Sb y , and indium and nitrogen for Ga 1-x In x N y As 1-y which gives us a band gap energy around 1 eV with a low strain and a maximum absorption, in fact we do not have only one value but a whole interval for both structures. In the second step we simulate the efficiency of both GaNAsSb and GaInNAs solar cells with the find concentration values in order to see which of the two structures will give a higher efficiency. We noticed that the results were obtained under AM1.5 illumination, 300 K and an ambient pressure. The two structures had a thickness of 300 nm. The N and P layers have a doping level of 1.1015 cm-3 and 1.1016 cm-3 respectively. This study gives us the possibility to produce multi-function solar cells. [ABSTRACT FROM AUTHOR]

In this work we study and optimize the single solar cell efficiency of GaN x As 1-x-y Sb y and Ga 1-x In x N y As 1-y deposed on GaAs. The solar cells are simulated, in the aim to find the best concentration of nitrogen and antimony for GaN x As 1-x-y Sb y , and indium and nitrogen for Ga 1-x In x N y As 1-y which gives us a band gap energy around 1 eV with a low strain and a maximum absorption, in fact we do not have only one value but a whole interval for both structures. In the second step we simulate the efficiency of both GaNAsSb and GaInNAs solar cells with the find concentration values in order to see which of the two structures will give a higher efficiency. We noticed that the results were obtained under AM1.5 illumination, 300 K and an ambient pressure. The two structures had a thickness of 300 nm. The N and P layers have a doping level of 1.1015 cm-3 and 1.1016 cm-3 respectively. This study gives us the possibility to produce multi-function solar cells. [ABSTRACT FROM AUTHOR]

The main limitations of the conventional solar conversion device is that low energy photons cannot excite charge carriers to the conduction band, therefore do not contribute to the device's current, and high energy photons are not efficiently used due to a poor match to the energy gap. Currently, Quantum Dot Solar Cells QDSC are one of the most active research fields in the third generation solar cells which can resolve this problem. In the present work, we are interested in modeling and simulating of both standard GaAs p-i-n solar cell and GaSb/GaAs Quantum Dot Solar Cell QDSC. When comparing 40-layers GaSb/GaAs quantum dot solar cell with standard GaAs solar cell, the conversion efficiency in simulation results increased from 16.48% to 22.46%, which is relatively 36.3% increase. Also, the absorption range edge of photons with low energies extended from 900 to 1200 nm. The results reveal that the GaSb/GaAs quantum dot solar cell manifests much larger power conversion efficiency than that of p-i-n junction solar cells. [ABSTRACT FROM AUTHOR]

Al 2 O 3 deposited using Atomic layer Deposition (ALD) technique is known as an excellent material for p-type silicon surface passivation. However a post-deposition annealing step is needed to make the passivation effective. Thanks to coupled electrical measurements (capacitance and photoconductance) and chemical analyses (X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectrometry (SIMS)) carried out on the same p-type Cz silicon sample, a closer explanation of this activation process is given. The presence of hydrogen and oxygen is correlated to the evolution of the electrical parameters and the minority carrier lifetime for 0 to 60 min 450 °C annealing. [ABSTRACT FROM AUTHOR]

Aim To evaluate the indications and results of preoperative radiotherapy (RT) on a series of selected patients treated at our institution with curative intent for a limb sarcoma (STS). Patients and methods From 05/1993 to 12/2011, 64 STS patients received preoperative RT. Results RT was delivered as a “limb salvage treatment” prior to surgery for the following reasons: as the preferential induction treatment in 53 patients (83%) or as a second intent (17%) after the failure of neoadjuvant systemic chemotherapy/isolated limb perfusion. Surgery was performed after RT in 54 (84%) patients and final limb salvage was performed in 98%. Musculo-cutaneous flap reconstruction was planned upfront in 44% patients, and 19% had a skin graft. Seven patients (13%) had a postoperative RT boost. Thirteen (20%) patients had grade (G) 3/4 adverse events, one after RT and 12 after surgery. At a median follow-up of 3.5 years, the 3-year actuarial overall survival (OS) and distant relapse (DR) rates were 83% and 31%, respectively. Two patients developed a local relapse and two a local progression (non-operated patients). In the multivariate analysis (MVA), histological subtype (leiomyosarcoma) and grade 3 were predictive of poorer survival. Patients with >3 month delay between the start of RT and surgery at our institution had an increased risk of DR in the MVA. Conclusion Induction RT should be personalised according to histological subtype, tumour site and risks-benefit ratio of preoperative radiotherapy and is best managed by a multidisciplinary surgical and oncology team in a specialist sarcoma centre. [ABSTRACT FROM AUTHOR]

This paper is expected at the study of Ga1-xInxP/GaAs based solar cell. The effects of indium concentration, lattice parameter mismatch and thickness of the SiO2 insulating layer on the characteristics and efficiency of the Ga1-xInxP/GaAs structure were investigated. We noticed that for higher indium concentration, the band gap energy decreases considerably. We found that the efficiency reaches 18% in a lattice-matched δ=50A. For a concentration x > 0.48, we have a compressive strain Δa/a > 0 which leads to a higher efficiency. For x=90%, δ=5nm and a strain equal Δa/a= 3%, we achieved an efficiency of 27%. The results show that light conversion efficiency has considerably boosted by varying insulating strain values. [ABSTRACT FROM AUTHOR]

In this paper, we report a simulation and investigation of a single In x Ga 1-x N/GaN axial multiple quantum well nanowire (MQWNW) solar cell of radius r = 190 nm and a length of L = 1165 nm. Our results have been shown that 15 In 0.15 Ga 0.85 N (QW) /GaN (barrier) periods is the maximum number that our structure can be supported with an optimal efficiency of about 1.65% achieved with ε = 1.5%. The insertion of MQWs in nanowire permits the growth of In x Ga 1-x N MQWs with high indium concentration of about 50% and ε = 5%. At this indium concentration, the optimal efficiency obtained was 1.70%. Moreover; the structure has been studied with respect to the nanowire radius. In this context, we have shown that the efficiency enhancement achieved through the increase of radius is attributed to the increase of photo-carriers. Study of polarization and proton irradiations has indicated the negative effect of polarization on structure performances and high resistance of III-N semiconductor materials against the radiations, respectively. From these novel structures we can improve solar cell performance for new applications. [ABSTRACT FROM AUTHOR]

• We report the modelling and optimization of a solar cell based on new material using SCAPS software. • A high absorption coefficient was found. • The influence of thickness, temperature, resistances and defects on the different electrical parameters. • A high conversion efficiency was obtained under optimum parameters. • A respectable compatibility has been shown compared with the results of wxAMPS software. Based on several semiconductor research, we have studied one of the new semiconductors, due to its exciting physical proprieties that in turn solve some problems in the photovoltaic's industry. We have divided this work into two parts. The first part, is to study the optical proprieties of ZnSnN 2 , as calculation of the absorption coefficient, bandgap, reflection coefficient, and transmission coefficient. As for the second part, a study of some parameters that affect the efficiency of p-CuCrO 2 (CCO)/ n-ZnSnN 2 (ZTN) solar cell using SCAPS-1D software, and our results are compared with the results of another software (wxAMPS), where results showed great compatibility with the presence of weak uncertainty. We have studied the influence of many parameters such as the thickness of the absorber layer (n-ZnSnN 2), the thickness of the buffer layer (p-CuCrO 2) , the temperature, the series resistance (R s), the shunt resistance (R sh) and the defect density on the performance of ZnSnN 2 solar cells which included in the real device. The photovoltaic parameters have been calculated using AM1.5G solar irradiance at the intensity of one sun, a temperature of 300 K, and considering the flat band condition at the interface. We have been achieving a high-efficiency of η ≈ 22% without defects. Given the characteristics of this new semiconductor ZnSnN 2 , which composed of earth-abundant, non-toxic and inexpensive element, as well as a high absorption coefficient, it can be considered as an alternative for PV and optoelectronic applications. [ABSTRACT FROM AUTHOR]

The aim of this modeling and simulation is to study the influence of the incorporation of nitrogen (N) and aluminum (Al) on the optoelectronic properties of the structure Al x Ga 1-x As 1-y N y /Ge, and then choose the right combination (N, Al) which gives us a better conversational efficiency of the junction(Al x Ga 1-x As 1-y N y /Ge), in this study, we simulated the effect of N and Al on the strain, the band gap, carrier mobility and structure efficiency where we based on theoretical models experimentally validate, It has been shown that the Al concentration slightly affects the stress and the band gap, but it has a significant influence on the incorporation of nitrogen and in a more homogeneous way introducing a dramatic decrease in the band gap what change considerably the absorption, carrier mobility and final yield of the structure. [ABSTRACT FROM AUTHOR]

A pulsed-DC sputtering process at room temperature has been developed for the deposition of the CIGS absorber layer. It uses a single quaternary target and is followed by a high temperature post-deposition annealing process. It has to be particularly noticed that no additional selenium supply was used. The annealed layers have shown a high microstructural quality: micrometric grain size, highly oriented (112) chalcopyrite phase, no phase decomposition and no Cu 2-x Se secondary phase at the surface. The use of such an absorber layer for the fabrication of 0.5 cm 2 solar cells has allowed reaching a conversion efficiency of 11.8% with an open circuit voltage of 558 mV, a short circuit current density of 32.1 mA·cm −2 and a fill factor of 65.8%. [ABSTRACT FROM AUTHOR]

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 E gmax (at the junction limit) to E gmin (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 V oc 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/cm 2 of short circuit current density, J sc , 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. [ABSTRACT FROM AUTHOR]

Considering the chalcopyrite solar cell fabrication process, the commonly reported substrate bending effect that is observed after thermal process, in a front side halogen lamp-based annealing configuration (Rapid Thermal Annealing –RTA- equipment), has been investigated. We first proposed a simple model explaining the substrate bending shape dependence on the initial stress state within the molybdenum (Mo) layer (free, tensile or compressive). Then, we showed that it is possible to overcome this issue by simply using a reactive (oxygen based) sputtering process for the deposition of the Mo layer. Finally, we showed that using a bilayer structure Mo(O)/Mo allows a more precise control of the flatness of the annealed samples. To understand the mechanisms governing such changes in substrate bending, structural and morphological material changes as a function of oxygen flow have been investigated by using X-ray diffraction and scanning electron microscope imaging, respectively. The elemental distribution throughout the Mo(O)/Mo bilayer structure thickness was also investigated. [ABSTRACT FROM AUTHOR]

This paper focuses on the simulation and optimization of electrical and optical properties such as current density-voltage (J-V ) , external quantum efficiency (EQE) and the photoluminescence spectra (PL) of InSb/GaAs quantum dot solar cell (QDSC). The InSb QDs have been inserted in the intrinsic region of p-i-n GaAs solar cell. Our results have been shown that 30 InSb/GaAs QD layers provide a relative enhancement of 22.35% and 29.30% of the short-circuit current and the efficiency, respectively. With the same number of the QD layers, the absorption range edge of low energy photons has been extended from 900 to 1400 nm. The electrical features obtained for InSb/GaAs QDSC have been compared with those obtained for InAs/GaAs QDSC in goal to show the better structure. The PL spectra has been also compared with experimental result for the same structure. Moreover, the QDSC has been optimized with respect to the thickness of QDs. The optimal conversion efficiency of 10 QD layers is improved from 14.85% to 18.30% by increasing the thickness of the QDs from 5 nm to 20 nm. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Room temperature deposited aluminium-doped zinc oxide thin films on glass substrate, using pulsed-DC magnetron sputtering, have shown high optical transmittance and low electrical resistivity with high uniformity of its spatial distribution after they were exposed to a rapid thermal annealing process at 400 °C under N 2 H 2 atmosphere. It is particularly interesting to note that such an annealing process of AZO thin films for only 30 s was sufficient, on one hand to improve their optical transmittance from 73% to 86%, on the other hand to both decrease their resistivity from 1.7 × 10 −3 Ω cm to 5.1 × 10 −4 Ω cm and achieve the highest uniformity spatial distribution. To understand the mechanisms behind such improvements of the optoelectronic properties, electrical, optical, structural and morphological changes as a function of annealing time have been investigated by using hall measurement, UV–visible spectrometry, X-ray diffraction and scanning electron microscope imaging, respectively. [ABSTRACT FROM AUTHOR]

• The lattice matching condition determination in order to obtain stable structure. • Physical and optical parameters determination at room temperature. • Emphasizing the impact of the absorption coefficient on the frequency response. • Frequency response optimization of the new pin photodiode structure. • Managing the frequency response limitations through the transparent layers. • Total frequency response calculation and highlighting its limitations. This paper reports on pin photodiode frequency response optimization based on In x Ga 1-x As 1-y N y quaternary lattice matched to GaAs. Two transparent layers are placed on p-side and n-side in order to manage the photodiode frequency response limitations. The lattice matching condition is calculated in order to obtain stable structure. The physical and optical parameters calculations are performed at room temperature showing the impact of nitrogen on the absorption coefficient. A stable structure, having 2 % of nitrogen and 6% of indium, allows to achieve a cutoff frequency of about 116 GHz and a capacitance of 5.21fF while the quantum efficiency is 41.59% for a depletion region thickness of about 0.55 µm. However, in case of depletion region thickness of about 0.625 µm, the cutoff frequency degrades to 98 GHz while the capacitance diminishes to 4.58fF and the quantum efficiency increases to 51.56%. In addition, a comparative study with literature results has been carried out in order to show the advantages of the proposed photodiode. This comparison affirms that the proposed photodiode based on InGaAsN lattice matched to GaAs exhibits high-speed photo-detection. This work allowed us to obtain a p-i-n photodiode with stable structure suitable for photo-detection at 1.15 µm. [ABSTRACT FROM AUTHOR]

In this paper, the CuInGaSe 2 based solar cell optimization has been established. We have simulated the structural strain effect. The effect of gallium concentration on the optical properties and the quantum external efficiency EQE was investigated. We also optimized the concentration x at low defect densities. The optimal gallium concentration is 0.30. We obtained an efficiency of the CuIn 0.70 Ga 0.30 Se 2 absorber solar cell around 24% with a strain ɛ = 0.64% and material defects densities equal to 1.2x1015cm−3. This work has been validated by theoretical and experimental studies. This study allows us to find a compromise between concentration x and defect concentrations in order to improve the performance and high efficiency of the solar cell. • The effect of structural deformation has been studied and simulated. • The effect of gallium on the optical properties and EQE was investigated. • We optimized the x concentration at low defect concentrations. • An efficiency of the solar cell which is equal to 24% with ɛ = 0.6% was obtained. • This work is validated by a theoretical and experimental study. [ABSTRACT FROM AUTHOR]

Abstract This work investigates the influence of the ion source (Au+ and Si+2 ions) of liquid metal alloy source-focused ion beam (LMAIS/FIB) on the nanopattering. Two sets of SiO 2 /Si nanopatterns with a width of 450 nm on Silicon on insulator (SOI) substrate are fabricated by 30 keV Au+ and Si+2 ions, respectively. To study this effect, the sputtering yield is calculated using the volume loss method from atomic force microscopy (AFM) profiles obtained for each set. The results of the sputtering yield were compared with theoretical results calculated from Yamamura model for normal incidence for validation. The comparison showed a good agreement between the two results with a relative difference of about 5.3% obtained using Si+2 ions. Highlights • The effect of AuSi LMAIS/FIB ions on nanomilling is investigated experimentally. • This effect has been shown through the study of sputtering yield. • The comparison has shown that Au+ ions are better for stable nanopatterns. • Our experimental results are in good agreement with calculated results. [ABSTRACT FROM AUTHOR]

Aluminum doped-zinc oxide (AZO) thin films were prepared on glass substrate by radio-frequency (RF) sputtering at room temperature. The sheet resistance, R sh [Ω] the resistivity, ρ [Ω·cm] and the 1/ f noise were studied as a function of thickness, t from 50 nm to 450 nm. The eddy current characterized the homogeneity of AZO thin films. The surface morphology has been analysed by atomic force microscopy (AFM). The 1/ f noise is normalized with respect to the bias, frequency and unit area, and C us is proportional to the sheet resistance R sh . Two configurations were used to characterize material and contact noise. The pressure effect of four point-probe on the material and the contact noise were also investigated. Our results show that the homogeneity of the samples increases as the film thickness increases and the resistivity decreases with increasing thickness and reaches the lowest value of 1 × 10 − 3 Ω cm at 450 nm. The average grain size and the root-mean-square roughness increases with rising thickness. The ratio K = C us / R sh is proportional to t 2 , which indicates that the mobility and the noise parameter α H shrink with the shrinkage of the thickness. [ABSTRACT FROM AUTHOR]

In this work we propose a modeling and simulation of core/shell p-i-n Si/Si 0.2 Ge 0.8 nanowire for photovoltaic. In the first step of this work, we have compared the core/shell p-i-n homojunction Si and heterojunction Si/Si 0.2 Ge 0.8 Nanowire (NW) solar cell having a length of 3 μm and a radius of 0.19 μm, by studying their current-voltage and external quantum efficiency (EQE). Our results have shown that blending Silicon with 80% of Germanium enhances relatively the short circuit current and efficiency by 3.04% and 8.48% respectively. In other hand, the absorption edge of Silicon NW has extended from 1100 nm to 1200 nm, with a gain of EQE of 15% obtained in this range. In the second part, we have tried to optimize the Si/Si 0.2 Ge 0.8 structure, by varying their radius and length. The corresponding results have indicated that a radius of 0.28 μm and a length of 10 μm are the optimal geometric parameters for any optimization of such structure. [ABSTRACT FROM AUTHOR]

The 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. • Type-I InGaSb/GaSb lasers, emitting at 2.3 μm are studied. • Optical/modal gain, confinement factor and the threshold current density are investigated. • A modal gain of 94 cm−1 can be reached at room temperature. • J th of 3 kA/cm2 is obtained under optical losses of about 50 cm−1 and T 0 =57 K at RT. • InGaSb/GaSb QWs are appropriate for mid-infrared lasers operating at T=300 K. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this investigation, the mechanical properties of the different layers composing a CuIn 1 − x Ga x Se 2 (CIGS) based solar cell were studied. Magnetron sputtering technique was used for the deposition of these layers except for the cadmium sulphide (CdS) layer which was deposited using chemical bath deposition process. We performed several indentation tests on the individual layers, i.e. molybdenum (Mo) back contact layer, CIGS absorber layer, CdS and alternative zinc sulphide oxide (ZnOS) buffer layers, and zinc oxide (ZnO)-AZO (aluminium-doped zinc oxide) transparent window layer; all were deposited on glass substrates. We report the values of the hardness ( H ) and of the Young's modulus ( E ) for each material, using indentation tests and an analytical model. The Mo layer remained the hardest and the most rigid, with H = 8.7 GPa and E = 185 GPa, while the CIGS layer has shown poor mechanical properties with H = 3 GPa and E = 58 GPa. On the other hand, the observed similarity in mechanical properties of the ZnO and ZnOS layers might be attributed to the similarity of their microstructures. [ABSTRACT FROM AUTHOR]

In recent years, the development of quantum well solar cells QWSCs (Quantum Well Solar Cells) has generated a great deal of interest. These configurations have shown good promise to optimize the low conversion efficiency of conventional solar cells because of the high rate of absorption losses present in them. In this work, we are interested in modeling and simulation of two different structures of solar cells, a simple solar cell based on silicon Si and a quantum well solar cell SiGe/Si. When a solar cell is compared to 80 quantum well layers of Si 0.8 Ge 0.2 with a pin solar cell based on Si. The short circuit current J sc increases from 23.55 to 37.48 mA/cm 2 with a relative increase of 59.15% found. In addition, the limit of the absorption band of the lower energy photons extends from 1100 nm to 2000 nm. [ABSTRACT FROM AUTHOR]

In this aim, we were interested in the optimization and simulation of pin-In 1−x Ga x N 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 J sc and the maximum output power. In return, the V oc decreases consequently. For In 0.50 Ga 0.50 N structure we observed that the current density and the maximum power are respectively around 19.50 mA/cm 2 and 27.50 mW/cm 2 with a ratio of 21.65 mA/cm 2 . Also it is shown that the incorporation of the quantum well in the active region results in an increase of J sc and P max but V oc remains unchanged. The incorporation of 50 quantum well structure in the In 0.50 Ga 0.50 N gives 22 mA/cm 2 of the current density and 32 mW/cm 2 of the maximum output power. The use of the structure based on In 0.50 Ga 0.50 N (MQW) induces an efficiency of 32%. We deduced that the relative efficiency is improved by 10.9%. [ABSTRACT FROM AUTHOR]

This paper proposes a method of modeling and simulation of InAs/GaAs-based quantum dots (QDs) for solar cell. The main objective is to find the growth parameters in order to produce an optimal double heterostructure using two semiconductor materials InAs and GaAs. We are interested in particular on the impact of the growth control parameters on the physical properties of the two-dimensional InAs mono-layer. We report here a complete but non-exhaustive analysis of the electronic states of the InAs based QDs layers grown on a GaAs substrate. In this work, the reader will find the modeling and the simulation results for both rectangular and elliptical geometries of InAs QDs. In the first part of this work, we provided the change of the electronic transition energy as a function of quantum dots’ radius whilst the second one concerns the absorption coefficient as a function of the incident photon wavelength. The curves we have obtained indicate clearly that the geometrical shape of the InAs QDs does significantly modify the various parameters above. We could therefore confirm that the more appropriate geometry is the elliptical one because of the higher performances. [ABSTRACT FROM AUTHOR]

In this study, we experimentally elaborated Copper- and Indium-doped Zinc Oxide (Cu: ZnO and In: ZnO) thin films at different temperatures (T 1 = 480 °C and T 2 = 520 °C), the doping ratio were varied between 0% and 8%. Using a low cost solution-based chemical deposition, we have developed a ZnO thin film deposition process that offers fine-control of the surface morphology. It consists in spraying a volatile compound of the material to be deposited on a substrate maintained at high temperature to cause a chemical reaction in order to form at least one solid product. Therefore, the proposed ZnO doped layer is highly promising for applications for the next-generation solar cells. [ABSTRACT FROM AUTHOR]

In this paper, we report a theoretical investigation of bandgap properties of GaAsNBi based materials on GaAs substrates. We look at the influence of nitrogen (N) and bismuth (Bi) concentrations on the position of conduction and valence bands; and we show that a split of the conduction band can take place with the incorporation of N at 5% under level, while a split of the valence band of both heavy and light holes sub-bands takes place after the incorporation of Bi at 14% under level. In order to compute the transition energies, we used the VBCA k.p 16×16 model. The N and Bi concentrations effects as well as the lattice mismatch value have also been taken into account. For a couple of N and Bi concentrations of 3% and 6%, we found strained gap energy around 0.68 eV. Furthermore, we have also shown that the absorption coefficient increases significantly when the N and Bi concentrations increase. [ABSTRACT FROM AUTHOR]

In this work, two process simplifications for n-type PERT (passivated emitter rear totally diffused) bifacial solar cells are investigated. Both are based on a single thermal treatment for elaborating boron and phosphorus doped regions aiming at reducing the number of high temperature steps of standard process. The first simplification shows a mixed co-diffusion from a gaseous source of phosphorus and a boron doped dielectric layer elaborated by low frequency plasma enhanced chemical vapor deposition (PECVD). The second exhibits two independent ion implantations, followed by a co-anneal/activation step. In both cases, implied open-circuit voltages are similar to standard process (~660–670 mV) and emitters allow good contacting by screen-printing ( ρ c =3.0–5.0 mΩ cm 2 ). PERT cells resulting from these processes show very promising performances with efficiency up to 19.7% on industrial 156×156 mm 2 pseudo square Cz wafers. [ABSTRACT FROM AUTHOR]

Pyramidal textures are commonly used to reduce reflections from silicon solar cells and improve light absorption by light trapping. They are generally modelled or characterised under normal incidence. In this work, a monolayer 3D ray tracing program taking into account the polarisation of light have been developed, validated and used to compute the directional-hemispherical reflectance versus the azimuth and incidence angles for both regular upright pyramids and inverted ones, with (1 1 1) facets. Results are given for a wavelength of 0.7 μ m . They show that this reflectance is not minimal at normal incidence but for an incidence angle near 20 ° and that upright pyramids can have a lower hemispherical reflectance than inverted ones for incidence angles in the middle range. The bihemispherical reflectance is 19.6% for regular upright pyramids and 20.7% for inverted ones. The effect of the pyramids aspect ratio on the hemispherical reflectance at normal incidence is also studied. This reflectance decreases with the aspect ratio of both textures. Above an aspect ratio of 0.51, inverted pyramids have a lower hemispherical reflectance. But their bihemispherical reflectance is lower only for aspect ratios below 0.23. [ABSTRACT FROM AUTHOR]

In this work, we have studied solar cells based on AlGaInAs/InP quaternary structure to describe the behavior of electronics components. To this end, we have developed a simulation program to study the gallium Ga and aluminum Al concentrations effect on respectively the lattice mismatch, the band gap energy, the absorption and the power delivered by the solar cell. This study allows us to compare between simulation and experimental results, once the cell parameters are optimized by a judicious choice of concentrations. This work allows us either to use nanotechnologies for solar cells. [ABSTRACT FROM AUTHOR]

Although solar cells operate under illumination, most electrical characterization methods are carried out in darkness, which implies some bias. In this work, we study the influence of light on the contact resistivity of the electron and hole contacts of a silicon heterojunction (SHJ) cell using the transfer length method (TLM) method in order to determine them in conditions representative of an operating solar cell at maximum power point. A specific fabrication process has been developed to preserve the passivation level. Therefore, we first focus on the patterning approach used for processing, and show that we can fabricate TLM samples with good passivation properties. Using simulations, we also discuss on the influence of inhomogeneities in the excess minority carrier spatial concentration on the TLM analysis. These inhomogeneities, due to shading, local damages in the passivation or to carrier drift under bias voltage make the measurement complicated to carry out without significant error. Our results suggest that the measurement is more precise in darkness and at very high injection levels, under rear illumination and a low voltage bias. • TLM samples for ρ C (e-) and ρ C (h+) measurement in SHJ cells can be fabricated while maintaining good passivation properties. • TLM measurements are carried out under illumination in order to probe ρ C (e-) and ρ C (h+) under operating conditions. • ρ C is influenced by the excess minority carrier density: it should preferably be extracted under operating conditions. • A meaningful characterization requires a good and homogeneous passivation across the TLM sample, minimal shading and low voltage bias. • Our simulations suggest a moderate impact of light on ρ C (e-) for standard c-Si doping levels. [ABSTRACT FROM AUTHOR]