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If similar evolutionary forces maintain intra‐ and interspecific diversity, patterns of diversity at both levels of biological organization can be expected to covary across space. Although this prediction of a positive species‐genetic diversity correlation (SGDC) has been tested for several taxa in natural landscapes, no study has yet evaluated the influence of the community delineation on these SGDCs. In this study, we focused on tropical fishes of the Indo‐Pacific Ocean, using range‐wide single nucleotide polymorphism data for a deep‐sea fish (Etelis coruscans) and species presence data of 4878 Teleostei species. We investigated whether a diversity continuum occurred, for different community delineations (subfamily, family, order and class) and spatial extents, and which processes explained these diversity patterns. We found no association between genetic diversity and species richness (α‐SGDC), regardless of the community and spatial extent. In contrast, we evidenced a positive relationship between genetic and species dissimilarities (β‐SGDC) when the community was defined at the subfamily or family level of the species of interest, and when the Western Indian Ocean was excluded. This relationship was related to the imprint of dispersal processes across levels of biological organization in Lutjanidae. However, this positive β‐SGDC was lost when considering higher taxonomic communities and at the scale of the entire Indo‐Pacific, suggesting different responses of populations and communities to evolutionary processes at these scales. This study provides evidence that the taxonomic scale at which communities are defined and the spatial extent are pivotal to better understand the processes shaping diversity across levels of biological organization. [ABSTRACT FROM AUTHOR]

Recombination is a central evolutionary process that reshuffles combinations of alleles along chromosomes, and consequently is expected to influence the efficacy of direct selection via Hill–Robertson interference. Additionally, the indirect effects of selection on neutral genetic diversity are expected to show a negative relationship with recombination rate, as background selection and genetic hitchhiking are stronger when recombination rate is low. However, owing to the limited availability of recombination rate estimates across divergent species, the impact of evolutionary changes in recombination rate on genomic signatures of selection remains largely unexplored. To address this question, we estimate recombination rate in two Ficedula flycatcher species, the taiga flycatcher (Ficedula albicilla) and collared flycatcher (Ficedula albicollis). We show that recombination rate is strongly correlated with signatures of indirect selection, and that evolutionary changes in recombination rate between species have observable impacts on this relationship. Conversely, signatures of direct selection on coding sequences show little to no relationship with recombination rate, even when restricted to genes where recombination rate is conserved between species. Thus, using measures of indirect and direct selection that bridge micro- and macro-evolutionary timescales, we demonstrate that the role of recombination rate and its dynamics varies for different signatures of selection. [ABSTRACT FROM AUTHOR]

The sex chromosomes have been hypothesized to play a key role in driving adaptation and speciation across many taxa. The reason for this is thought to be the hemizygosity of the heteromorphic part of sex chromosomes in the heterogametic sex, which exposes recessive mutations to natural and sexual selection. The exposure of recessive beneficial mutations increases their rate of fixation on the sex chromosomes, which results in a faster rate of evolution. In addition, genetic incompatibilities between sex‐linked loci are exposed faster in the genomic background of hybrids of divergent lineages, which makes sex chromosomes contribute disproportionately to reproductive isolation. However, in birds, which show a Z/W sex determination system, the role of adaptation versus genetic drift as the driving force of the faster differentiation of the Z chromosome (fast‐Z effect) and the disproportionate role of the Z chromosome in reproductive isolation (large‐Z effect) are still debated. Here, we address this debate in the bird genus Ficedula flycatchers based on population‐level whole‐genome sequencing data of six species. Our analysis provides evidence for both faster lineage sorting and reduced gene flow on the Z chromosome than the autosomes. However, these patterns appear to be driven primarily by the increased role of genetic drift on the Z chromosome, rather than an increased rate of adaptive evolution. Genomic scans of selective sweeps and fixed differences in fact suggest a reduced action of positive selection on the Z chromosome. [ABSTRACT FROM AUTHOR]

Aim: Evaluating the similarity of diversity patterns across micro‐ to macroevolutionary scales in natural communities, such as species–genetic diversity correlations (SGDCs), may inform on processes shaping community assembly. However, whether SGDCs not only hold across communities but also across lineages has never been explored so far. Here we investigated SGDCs across co‐distributed taxa for different spatial components (α, β, γ), and formally tested the influence of dispersal traits on β‐SGDCs. Location: Western Indian Ocean. Time period: 2016–2017. Major taxa studied: Tropical reef fish species with contrasting dispersal traits. Methods: Using double‐digest restriction‐site associated DNA sequencing (ddRADseq) Single Nucleotide Polymorphism data for 20 tropical reef fishes and distribution data of 2,446 species belonging to 12 families, we analysed the correlations between within‐species genetic diversity and within‐family species diversity (i.e., lineage diversity) for the three spatial components (α, β, γ‐SGDCs). We then related the strength of β‐SGDCs per species to proxies of larval dispersal abilities. Results: We detected positive and significant lineage‐based SGDC only for the β component, that is, the families showing the greatest level of species turnover among sites contain the species with the greatest levels of genetic differentiation. We showed that the Monsoon Drift mainly explained the β‐diversity patterns at both intraspecific and interspecific levels. Higher β‐SGDCs were found for species with short pelagic larval duration and weak larval swimming capacity. Main conclusions: Our study reveals a strong correlation between genetic and species β‐diversity, a result explained by the presence of a 'soft' barrier and mediated by larval dispersal processes. This suggests that vicariance and dispersal limitation are major processes shaping β‐diversity patterns from microevolutionary to macroevolutionary scales in tropical reef fishes. [ABSTRACT FROM AUTHOR]

Hybridization is an evolutionary process with wide‐ranging potential outcomes, from providing populations with important genetic variation for adaptation to being a substantial fitness cost leading to extinction. Here, we focussed on putative hybridization between two morphologically distinct species of New Zealand grasshopper. We collected Phaulacridium marginale and Phaulacridium otagoense specimens from a region where mitochondrial introgression had been detected and where their habitat has been modified by introduced mammals eating the natural vegetation and by the colonization of many non‐native plant species. In contrast to observations in the 1970s, our sampling of wild pairs of grasshoppers in copula provided no evidence of assortative mating with respect to species. Geometric morphometrics on pronotum shape of individuals from areas of sympatry detected phenotypically intermediate specimens (putative hybrids), and the distribution of phenotypes in most areas of sympatry was found to be unimodal. These results suggest that hybridization associated with anthropogenic habitat changes has led to these closely related species forming a hybrid swarm, with random mating. Without evidence of hybrid disadvantage, we suggest a novel hybrid lineage might eventually result from the merging of these two species. [ABSTRACT FROM AUTHOR]

This paper focuses on studying and simulating a GaAs1-xPx/Si1-yGey/Ge triple-junction solar cell structure. First, the strain and the bandgap energy associated to the SiGe layer have been studied. The optimal germanium concentration is 0.88 with a strain around 0.45%. Then, the phosphor concentration effect on the strain and the bandgap energy of the upper layer GaAs1-xPx/Si0.12Ge0.88 has been optimized. At room temperature, the optimal output parameter reach Jsc=34.41mA/cm², Voc=1.27V, FF=88.42% and =38.45% for an absorber thickness of 4.5µm and x=0.47, with a strain that doesn't exceed 1.5%. This study has enabled us to design a high-efficiency, low cost 3J solar cell. [ABSTRACT FROM AUTHOR]

We present the design, implementation and characterisation of an integrated surface plasmon resonance (SPR) biosensor chip involving diffractive optical coupling elements avoiding the need of prism coupling. The integrated sensor chip uses the angular interrogation principle and includes two diffraction gratings and the SPR sensing zone. The theoretical design is presented as well as the fabrication process. Experimental results (response of a reference water droplet and phosphate-buffered saline/water kinetic) are presented and compared with those obtained with the classical Kretschmann prism coupling setup. We believe that this prism-free architecture is perfectly suitable for low-cost and reproducible SPR biochemical sensor chips since the sensing zone can be functionalised as any other one. [ABSTRACT FROM AUTHOR]

Hydrogen SilsesQuioxane is recently known as a negative tone e-beam resist for Si wafer technology. For III/V semiconductors, as GaAs reported here, the usual TMAH developer does not result in a good quality patterning; in order to overcome that, this paper presents the use of KOH-based developer as alternative processing. Its process conditions, that are described hereby, lead to higher contrast combined to higher process latitude. Finally, single lines down to 60 nm width and nanometer-gratings are investigated with a minimum of roughness illustrated by an AFM study. [Copyright &y& Elsevier]

We present a versatile bondpad report process that can be used either for high relief compound semiconductor devices or interconnection schemes. It is based on the use of two different polymers (photoresists) and one electroplating step. [Copyright &y& Elsevier]

Focuses on a study which examined a microwave microstrip line terminated by a laser illumination that alters the behavior of the microwave device. Description of the procedure; Explanation of the physical phenomenon; Simulation and results.

We have shown that, if a microstrip line deposited on silicon is illuminated at its end, a nonlinear load is obtained which behaves in microwave like a “photoinduced varactor.” We have obtained this result experimentally, and by solving the Poisson's equation and the two carrier continuity equations. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 10–13, 2000. [ABSTRACT FROM AUTHOR]

Using a 219 bipolar physical model a comparison is made between GaAs and AllnAs/GaInAs MSM PD performance (cutoff frequency and quantum efficiency) as a function of the device parameters. This covers the applied potential, electrode spacing, absorbing layer thickness, and heterojunction effect. We also reported that for millimeter-wave applications we can expect higher operating frequency using an AllnAs / GaInAs MSP PD, whereas we can expect higher quantum efficiency using a GaAs MSM PD. [ABSTRACT FROM AUTHOR]

Static and dynamic behaviors of multielectrode lasers are, for the first time, studied using an equivalent circuit model. The model is based on the monomode rate equations and the Fermi integral. The potential controlled absorption in the active-region quantum wells and its saturation are included as well as the different carrier recombination mechanisms. The model predicts a higher resonance amplitude and a -20-dB/decade slope above resonance instead of the commonly known -40-dB/decade slope for direct current modulation and consequently higher cutoff frequencies are to be expected for such structures. We also discuss briefly the impedance level of such structures as well as the different phenomena to be taken into account far a more precise representation. [ABSTRACT FROM AUTHOR]

We present theoretical and experimental results on an analog-fiber optic link using commercially available, or so, optoelectronic devices. The directly modulated experimental link operates at 850 MHz and an improvement of 11.5 dB on insertion loss has been obtained using passive reactive networks. The experimental optical link has shown an electrical insertion loss of -8 dB. The respective contributions of emitter and receiver modules have been clearly pointed out. [ABSTRACT FROM AUTHOR]

We present a new large/small signal equivalent circuit for semiconductor lasers, valid for above- as well as below-threshold operating conditions, based on the monomode rate equations and a polynomial approximation of Fermi integral. The model is thus valid for conditions of large injection. Results obtained by this model match perfectly those obtained by numerical integration of the rate equations. The equivalent circuit is easy to implement and solve on a nonlinear circuit analysis software such as SPICE and consequently allows the study of the parasitic effects as well as the laser behavior in complex circuits. Comparison between this model and previously published models is presented. The model is applied to the study of various heterojunction laser diodes, the experimental results of which have been published elsewhere. [ABSTRACT FROM AUTHOR]

A report is presented on the optical propagation loss of waveguides based on InP nanowires embedded in a benzocyclobutene matrix and fabricated through a wafer bonding process. Propagation loss was evaluated on waveguides of varying width; it can be as low as 0.8 dB/mm for a 300×300 nm InP. [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]

An adhesive wafer bonding technique for the fabrication of nanophotonic guiding structures, the design of which consists of a III-V semiconductor core buried in a polymer matrix, is reported. The bonding was realised owing to benzocyclobutene. Nanostructures are perfectly embedded in the void-free matrix to form high density photonic circuits. [ABSTRACT FROM AUTHOR]

It is shown that local and large lattice mismatch epitaxies could be useful techniques for the fabrication of optoelectronic integrated circuits. As an example, we fabricated a monolithic resonant photoreceiver which associates a long-wavelength metal-semiconductor-metal photodetector, a GaAs MESFET preamplifier, and an inductor. The GaAs / GaInAs heteroepitaxy needed for the photodetector wax selectively grown using a SiO[sub2] mask and the entire circuit was fabricated on a silicon substrate. Compared to a PIN photodiode loaded with a 50-ω resistor, more than 10 dB gain was measured at 7 GHz in a microwave optical link. [ABSTRACT FROM AUTHOR]

We have measured the noise performance of GaInAs PIN photodiodes in the microwave frequency range. We show that the frequency response of the photodetector can be deduced from their photocurrent shot noise spectra. The noise level has been measured using a setup which is based on heterodyne microwave mixing. [ABSTRACT FROM AUTHOR]

The first fabrication of a thin and short GaAs metal-semiconductor-metal photodetector monolithically integrated with a GaAlAs optical inverted rib waveguide on a semi-insulating GaAs substrate is reported. An only 0.2-μm-thick and 100-μm-long GaAs absorbing layer is needed to detect 90% of the optical signal at 0.85 μm wavelength. Static, dynamic, and noise measurements have been performed and a bandwidth in excess of 15 GHz is obtained. [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]

Abstract In this work, we theoretically investigate the structural dependence of intersubband absorption of InGaAsSb/GaAs single quantum well structures. We begin by analyzing the impact of In and Sb incorporation on the critical thickness, conduction band offset and band gap energy. The first two electron energy levels E 12 and the corresponding wavelength were made for the In x Ga 1− x As 1- y Sb y /GaAs system and are analyzed in detail by solving the Schrödinger equation. Also, we have investigated effects of composition and well width on the intersubband absorption. In addition, the wavelength and absorption coefficient of the ISBT can be adjusted and optimized by changing the composition and the width of the SQW. Finally, strain effects on intersubband absorption and on the peak response wavelength have also been systematically studied. Our study shows that InGaAsSb/GaAs SQW will play a key role in research of electronics and photonic devices in the future. Highlights • Studied the effects of structural parameters on the Intersubband transition of InGaAsSb/GaAs QWs. • Absorption coefficient dependency on the InGaAsSb structural parameters has been investigated. • The effects of these parameters are numerically studied. • Effect of the strain on peak wavelength and on the maximum absorption has been verified. • InGaAsSb/GaAs is a good candidate as a novel material system for optoelectronic intersubband devices. [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]

Presents information on a study which evaluated a monolithic integrated circuit associating a Schottky photodiode and a field-effect transistor which has been fabricated for the first time, on gallium[sub0.49]indium[sub0.51]phosphorus/gallium[0.47]indium[sub0.53]arsenic strained heteroepitaxial material. Description of the dark current of the photodiode under reverse bias voltage; Measurement of photodiode capacitance; Proposed improvements to obtain better performance of the device.

The fabrication and characterisation of a GaAs based electroabsorption modulator for radio over fibre applications is reported. It is designed to work as a transmission type device for multimode fibre networks at 850 nm wavelength and to act so, it has been transferred to a transparent silica substrate (after complete removal of the GaAs substrate). [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]

We describe an optically controlled microwave attenuator based on a microstrip reverse directional coupler where optical illumination modifies the loads at the coupling and transmission ports. A tunable attenuation up to 10 dB was measured at the center frequency, Experimental and theoretical results are compared and agree well. [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]

In this work, the design and simulation of an GaInP single junction solar cell are presented. The work focuses mainly on the optimization of the PN junction thicknesses of n-base and pemitter cell layers in order to improve the cell conversion efficiency. Besides this optimization, the layers of the cell window AlGaInP and an added buffer AlGaAs were also optimized in term of doping and thicknesses using Atlas tool of SILVACO TCAD. The cell is simulated under the conditions of 1 sun and AM1.5G solar spectrum at 25°C. The simulated GaInP solar cell demonstrates an efficiency (η) of 22.42%. The cell shows different electrical behaviors in terms of short circuit current density (Jsc), open circuit voltage (V∝), fill factor (FF), and external quantum efficiency (EQE). The obtained results are compared with those reported in the literature. Simulation results of the cell are: a Jsc of 18.35 mA/cm2, V∝ of 1.41 V and FF of 86.81% with the corresponding n-base layer and pemitter layer thickness of 0.410 µm and 0.174 µm respectively and the total device thickness of 0.65 µm. According to these results, the proposed cell demonstrates an improvement in the efficiency and a reduction of the used GaInP material. [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]

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. [ABSTRACT FROM AUTHOR]

Summary: 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. [ABSTRACT FROM AUTHOR]

Purpose: The SPUR (Social, Psychological, Usage and Rational) Adherence Profiling Tool is a recently developed adaptive instrument for assessing key patient-level drivers for non-adherence. This study describes the SPUR questionnaire's finalization and psychometric evaluation. Patients and Methods: Data were collected through an online survey among patients with type 2 diabetes included by general practitioners and diabetologists in France. The survey included four questionnaires, SPUR and three validated adherence measures: BMQ, MARS and ACCEPT. Item-level analysis and a partial credit model (PCM) were performed to refine the response option coding of SPUR items. The final item selection of SPUR was defined using a PCM and a principal component analysis (PCA). Construct validity, concurrent validity and known-groups validity were assessed on the final SPUR questionnaire. Results: A total of 245 patients (55% men, mean age of 63 years) completed the survey remotely and were included in this analysis. Refining response option coding allowed a better discrimination of patients on the latent trait. After item selection, a short, an intermediate, and a long form composed the final SPUR questionnaire. The short form will be used to screen patients for risk and then the other forms will allow the collection of further information to refine the risk assessment and decide the best levers for action. Results obtained were supportive of the construct validity of the forms. Their concurrent validity was demonstrated: moderate to high significant correlations were obtained with BMQ, MARS and ACCEPT scores. Their known-groups validity were shown with a logical pattern of higher scores obtained for patients considered non-adherent and significant differences between the scores obtained for patients considered adherent versus non-adherent. Conclusion: SPUR is a valid tool to evaluate the risk of non-adherence of patients, allowing effective intervention by providing insights into the respective individual reasons for lack of adherence. [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]

This study aims to investigate the different optical properties of the ZnSnN 2 absorber layer such as absorption, reflection and transmission coefficients. The effects of the ZnSnN 2 absorber layer thickness, temperature,and defect density on electrical parameters such as short circuit current density, open circuit voltage, fill factor and efficiency have also been studied in detail. These factors play an important role in the performance of the ZnO/CdS/ZnSnN 2 /Si/Mo structure. The highest efficiency of about 23.32 % is achieved without defects in the ZnSnN 2 absorber layer, under the 1-sun AM1.5 solar spectrum, by applying the flat band condition and considering the strain values of 0.37 % (ZnSnN 2 /Cds) and 7.17 % (ZnSnN 2 /Si). In addition to high efficiency, the ZnSnN 2 has a high absorption coefficient. This device will play a crucial role in optoelectronic applications. This structure is a promising candidate for low cost and high efficiency photovoltaic technology. [ABSTRACT FROM AUTHOR]

The study reported here deals with the exploitation of perfluorinated graded index polymer optical fiber bandwidth to add further services in a home/office network. The fiber properties are exhibited in order to check if perfluorinated graded index plastic optical fiber (PFGI-POF) is suitable to support a multiplexing transmission. According to the high bandwidth length of plastic fibers, both at 850 nm and 1,300 nm, the extension of the classical baseband existing network is proposed to achieve a dual concept, allowing the indoor coverage of wireless signals transmitted using the Radio over Fiber technology. The simultaneous transmission of a 10 GbE signal and a wireless signal is done respectively at 850 nm and 1,300 nm on a single plastic fiber using wavelength division multiplexing commercially available devices. The penalties have been evaluated both in digital (Bit Error Rate measurement) and radiofrequency (Error Vector Magnitude measurement) domains. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we report new results dealing with the wavelength multiplexing transmission scheme over the OM4 high modal bandwidth multimode fiber. Fiber bandwidth measurements both at 850nm and 1300nm clearly show the huge bandwidth/length product of this fiber. The simultaneous transmission of a high data rate baseband signal (10GbE) at 850nm and a radiofrequency MultiBand Orthogonal Frequency Division Multiplexing Ultra-Wide Band (band group 5–10GHz) MB-OFDM UWB signal (480Mbps) at 1300nm is presented. The measurements – Bit Error Rate (BER) for the 10GbE signal and Error Vector Magnitude (EVM) for the MB-OFDM UWB signal – that are hereby reported show safe results under the requirements of the corresponding communication standards; they give this architecture an affordable approach for home/office networking at high data rate in a joint fixed and wireless environment. [ABSTRACT FROM AUTHOR]

Abstract: A radio over fiber system using the fluorinated based polymer multimode fibers (PMMF) is presented in this paper for the enhancement of the indoor coverage of the multiband orthogonal frequency division multiplexing ultra-wideband standard (MB-OFDM UWB) inside a building. A preliminary part related the cost analysis owing to glass and polymer multimode fiber deployment inside a fiber network is reported. The study of the physical properties of the polymer optical fibers (core diameter, numerical aperture, differential mode delays, modal bandwidth…) is firstly performed in order to effectively exhibit the potentialities and the robustness of such fibers to be used in a low cost radio over fiber system. The DMD measurements of four fluorinated based polymer optical fiber are reported. The designed system operates at 850nm with commercial off the shelf (COTS) devices combined to the intensity modulation/direct detection technique. The opportunity of using polymer fibers and COTS components to improve the indoor coverage of the MB-OFDM UWB standard is so reported by the measurement of the Error Vector Magnitude or the Relative Constellation Error variation as a function of the system parameters (RF power, optical attenuation, fiber length…) as well as the compliance of the eye diagram with the mask testing. By the way, the transmission performance of both 200 and 480Mbps signals is demonstrated over up to 200m link length of polymer multimode fibers: transmission penalties are quantified by relative constellation error with values under the standard requirements. A comparative study with classical OM2 50μm based glass multimode fiber having the same bandwidth/length product than the PMMF is done. [Copyright &y& Elsevier]

The authors present the design, fabrication and characterisation of passive photonic components using InP optical wire technology. These components are straight and curved waveguides as well as Y-junctions. Their ultimate use is to be integrated within active nanophotonic functions and this is implicitly targeted in the different parts of this process work. First, propagation and excess losses because of a bend or Y-junction are modelled using a beam propagation method or a finite difference time domain method. Then, the technological process used to fabricate these components is presented; it is mainly based on e-beam direct writing and inductively coupled plasma deep etching. Finally, the different losses are measured and results are compared with the theory. The authors demonstrate, thus, that the use of submicron waveguides (or optical wire) can lead to very compact optical passive functions on InP since very small radius bends and wide angle Y-junctions showed almost low excess loss. [ABSTRACT FROM AUTHOR]

To be faster and more precise than the numerical technique for the computation of the photo-induced plasma in semiconductor, an analytical solution has to be developed. In this article, the Hankel transform is used to simplify the solution of the differential equation of second order with nonsconstant coefficient, known as the diffusion equations. The resulting expression of the 3D carrier density includes all the physical parameters of the substrate and the laser beam as well. A parametric study was also feasible using the developed expressions. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1718–1721, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21754 [ABSTRACT FROM AUTHOR]

This paper presents the first investigation of a novel method to obtain an apodization effect on common InP ridge waveguide filters. It consists of the use of particular sampled gratings. Such apodized filters measured transmission spectra present an enhanced rejection of about 20 dB of the adjacent sidelobes, which experimentally validate the concept. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1627–1630, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21682 [ABSTRACT FROM AUTHOR]